okay, I stand corrected but I still say it would better serve as a subclass to a generic animist class for ease of structure, plus it is a fairly tight and constrained idea less so than barbarian but honestly not full class worthy.
what are bards supposed to be anyway as you seem to know?
I'm going to heavily paraphrase Professor John T. Koch's
Celtic Culture: A Historical Encyclopedia here, as that's a very complicated question. Just a note that he's got 14 pages devoted to the subject in his first volume of the encyclopedia, so this is an overview of an overview.
Bard is a complicated term, like Druid of course. One might distinguish between the the medieval insular Celtic usage of the term to mean a poet versus the functions of the Bard in Celtic societies of Antiquity (let alone what their function may have been, if any , during the rise of Celtic culture in Bronze Age Atlantic Europe and/or Halstatt Central Europe).
The classical antiquity accounts of Gaul spoke of the Bards as professional praise poets who severed the Chieftains directly. Posidonius in 1st Century BCE had first hand experience in southern Gaul and his unfortunately lost
History is quoted directly numerously in extant texts. Athenaeus quotes or paraphrases Posidonius as describing them this way:
..the Celts have with them, even in war, companions whom they call parasites ['those who dine at another's table']. These poets recite their praises in large companies and crowds, and before each of the listeners according to rank. Their tales are recounted by those called bards, poets who recite praises in song.
Diodorus Siculus quotes Posidonius as grouping Bardtogether with Druids and 'seers' (from whence we get the name of the modern Neo-Druid organization OBOD - the Order of Bards, Ovates, and Druids; vātēs or Ovates is a Latin approximation of the Gaulish word for seer *owātis, akin to Old Norse o∂r "poetry", Old English woth "song", and from which descends Irish fáith "prophet" and Welsh Gwawd "satire" - but which used to mean "inspired verse, song, song of praise."
[The Gauls] have lyric poets called Bards, who, accompanied by instruments resembling lyres*, sing both praise and satire. They have highly honoured philosophers and theologians called Druids. They also make use of seers, who are greatly respected.
*presumably this is a reference to what we now call the Celtic Harp.
And Strabo speaks also to the seer/Bard/Druid connection, though he speaks in trichotomy as well, directly using the term vātēs:
As a rule, among all the Gallic peoples three sets of men are honoured above all others; the Bards, the Vātēs, and the Druids. The bards are singers and poets, the vātēs overseers of sacred rites and philosophers of nature, and the Druids, besides being natural philosophers, practice moral philosophy as well.
In that sense, to Strabo, a D&D Druid would be a Vātē and a Druid would be a D&D Nature Cleric.
Note that etymologically speaking the Vātēs and the Bards are one the same, and from classical accounts there is much overlap between the seer and the Druid - there are may other accounts of receiving prophecies from Druids. This may indicate that Bards and Druids were separate but related roles within a Brahmin-like priestly class, despite the dominance of the warrior class over the political theatre. Julius Caesar speaks quite a bit about the Druids but mentions not the Bards or Vātēs. This could be a suggestion that he conflated the three, but he certainly had an independent account from Posidonius.
The Bardic function of praising the patron and the relationship between Bard and patron survived through medieval into early modern times in Ireland, Wales, and the Scottish Highlands.
The Proto-Celtic term is reconstructed as Bardos; this seems derived from PIE root *gwer(a) meaning "to raise the voice, to praise, to extol, to welcome." This same root gave rise to Sanskrit jaritár "singer, praiser", Avestan aibijaretay "laudator", and Latin grātēs "thanks".
So from this early Celtic context of praise poetry in service of a patron warchief, we have semi-separate medieval evolution of the Bard in the Gaelic and Brythonic traditions. In medieval Wales (which covered everywhere northwest of a diagonal line from Gloucester to the Humber and south of the Firth of Forth), you had the Gogynfeirdd in the 12th and 13th Centuries CE that produced nearly 13k lines of extant poetry, most of which eulogizes princes, noblemen, and less often, the daughters of said nobles.
Cynddelw tells Rhys ap Gruffudd that 'without me, no speech would be yours' - that is, it' is the verse of the Bardd that creates history and a lasting legacy for the warrior, otherwise he is forgotten. The ability to craft a narrative around the deeds of a great hero or a great villain speaks to the fundamental function of the Bardd in medieval Cymric society.
St. Gildas ap Caw, the famous monk who wrote of Arthur's 12 battles with the Saxons and Picts (and whose Goddodin/Votadini/Pictish father is traditionally seen as an enemy of Arthur), spoke that the wicked Prince Maegwn Gwynedd preferred to listen to the 'empty praises of himself from mouths stuffed with lies and foaming phlegm' than to the praises of God, clearly casting the Bards praise of the petty rulers in contrast to the monastic orders' songs to their deity. Remember, however, that most Celtic deities are conflated with human warleaders, druids, and their allies; whether they were humans first elevated to the role of deities on virtue of sheer prominence of their deeds in the bardic cycles or whether they were gods worshiped by the druids diminished by Christianity into pagan heroes or Christian knights of the round table etc, or whether they were bit of both, the Bardic tradition is essentially perfunctory to the role of the divinity. The Heroes and the Gods do not have a clear distinction. A hero who is heroic enough may be worshiped as a god, much as Heracles was in Greece and Rome. It is the Bards who create that narrative of heroism. But this account also shows the growing rift between respect for the Bards and disdain for the Bard, something we see with spoonyisms to this day in D&D.
After the fall of the last native Prince of Wales, Llywelyn ap Gruffudd in 1282, the cymric poets continued to compose eulogies and elegies for the honour of the gentry, but despite a continuity of theme and form, their vital importance to the social fabric faded given the fading of their patron's power.
Then there's not much of a satirical tradition recorded in medieval Wales, though this may be due to the art of praising having a purpose for the history books while the art of the insult… not so much. There is also the idea that arose in the late medieval period that the maligning and discrediting and satirizing poetics is a lesser form of entertainment and not the true poet. This stands in contrast to the power of the bard in early medieval poetry to discredit the patron who slights the Bardd, suggesting that the nobility eventually took that power away from the Bards. Finally, by the late medieval period you have arising a formalized Bardic Order, or guild of poets, standing in contrast to the household Bards devoted to a single patron.
Perhaps chief of the terms one might want to understand with with the Welsh Bardd is the Welsh term "awen" - the spirit of prophecy and spark of inspiration that the Bard Taliesin acquired from sipping form the cauldron of the witch/druidess Cerridwen, leading him to be the most celebrated of Bards and counselors to Kings like Arthur.
In medieval Ireland, on the other hand, you have a distinction between the high poet file and the inferior poet bard. But the bardic functions of eulogy, elegy, praise poetry, and most importantly satire lasted longer in Ireland and served incredibly important functions. It seems that the filid got their education in the Christian monasteries and are a development of the later Christianized poetic traditions that diminished the earlier bardic ones. Much of what we know of the Irish cycles of mythology and heroes and invasions come from bardic oral traditions that eventually were written down by Christian scribes. And a true Bardic Order professional guild had emerged as early as the 8th Century CE. The education of the bard would be that of apprenticeship, usually patrilinial, until the 14th Century when schools of poetry were established.
We could also speak to the Bard baile of Highland Scots, the village poet working within a defined locale and compoising in a generally traditional form to relate specifically to that community. This would mostly be performed in a local public house dedicated to music, dancing, the telling of tales, and the trading of information. This type of Bard's function were entertainment and social commentary, but also as an intermediary between the village and the changing world around them.
Finally, we can speak to the Romantic Celtic revival interest in Bards, which leads us directly to the D&D Bard. The function emphasised in these modern periods is the casting of a spotlight on others, and in the Romantic period to present day, the Bard often has become the protagonist of the story int eh sense of being the character whose lens we see the tale through. Unlike the hero, who may live or die per the needs of the story, the Bard must survive to tell the tale to the audience, but who may grow old and ached with much loss. The bard is a bearer of the nostalgia in their elegies to the lost heroic age.
The prominence of Oisín in the understanding of the Bard in Romantic stories is not without note; in the story of Oisín in Tír naNog, the famous bard-son of Fionn macCumhail falls in love with a fairy princess, travels to the Otherworld, but out of desire to see his home and family again returns back, only to find that centuries have passed. The moment he steps off his magical horse, he ages into a decrepid old man, the actual centuries catching up to him, though he had only experienced it as a few months. He passes the tales of the Fenian Cycle onto St. Patrick, and dies, in hopes that the world will remember his father and their companions deeds. This tale predates the Romantic period, but James MacPhersons Scots Ossian cycle was composed in the Romantic period and became one of the defining influences on Celtic revivalism. The rise of the Merlin figure from the Myrddin Wyllt (aka Lailokan), Myrddin Emrys, and Taliesin stories fulfills a similar role in the Romantic stories; so much so that that by TH White's
The Once and Future King, Merlin is living his life backwards, a world seeped in loss.
The ancient bard becomes a figure of knowledge and wisodm, a visionary or occult being. He is a solitary being with a burden of sorrow, distracted from the present struggles of the world by the loss of his family and firends in the centuries that have passed. This reverential treatment created a cognitive dissonance with the earlier pragmatic view of the bard as the whip of the Celtic insurgents, pirates, and raiders. And then we have the Celtic romantic forge artists, like MacPhearsons but also like Iolo Morgannwg's forged Welsh triads and tales, and you have a sort of fall from grace of the literary Bard.
And thus we have the most enduring legacy of the Bard - a tale of contrasts between the praise and demonisation, between elegance and reverence and spoonyism and spoofery. Of conservatism and loyalty to an old order, and the progressivism and irreverentism that the Bard's chaotic satire brings. And all the while, the 'druidic' traits of the Bard have proved remarkably resilient, the Bard as seer. This is the role of the Fool card in Tarot: the fool IS the only one who can speak truth to the monarch. It is the journey of the fool to become the sage. The Bard develops into the Druid with age. That is the modern archetype of the Bard, and it continues to this day in popular media.