Gammadoodler
Hero
Sure, litigating any number of potential fictional scenarios is basically impossible.Erm.... Okay. Let's take a look.
I listed the sort of things I was thinking in the post above. I didn't list them originally as I didn't think we were going to get down to minutia as I thought this was a pretty hand wavy kind of discussion. But yes, I did assume some basic magic items for an epic level character. This might not be appropriate for some super low magic item settings I guess.
I also wouldn't expect an entire army to be fitted out with chain & shield (that's very expensive) but again, I suppose it depends on the setting. Yours could be extraordinarily well supplied.
Most armies also don't call down ranged attacks on their own troops location just to try to hit one guy standing in the middle of hundreds of their own guys..... Again, I suppose your campaign setting could be unusual in this regard. They might be very bloodthirsty.
But honestly, we can tailor the example however we like, but given the infinite possibilities of campaign settings, character builds, and actual player-DM storytelling interactions, to me there is plenty of room for this legendary swordsman to be able to acquit himself well in this scenario (or versions of it).
What is your fundamental disagreement with this?
My fundamental disagreement is that you've chosen something that I do think a high-level martial should be good at. And it is probably the scenario which is least suited to the abilities they receive....unless you prop them up with a host of magic items...and you assume that they are facing an army of commoners whose archers are unwilling to fire until all the commoners in front of them are dead.
And I didn't get into it before, but consider the comparison to the magic fighter who is supposed to be middling with the sword but with a little bit of magic.
No fancy magical equipment, matches the AC of our fully-kitted legendary swordsman with a first level spell (shield). Can impose non-stop disadvantage for a minute (greater invis), has area denial/damage capabilities in things like fireball and wall of flame.
Our spellcaster fighter is just...so...much...better for this, and it's not even the only thing they can be good at.
I realize that we haven't really given out "mundane" swordmaster a subclass, but I can't think of any that would even really come close in terms of either damage potential or survivability...and that sucks.