I don't see how this class adds any prestige to a straight Bard. Actually, I think this PrC is heavily on the bland and the weak sides. I mean this in a strictly mechanical sense, I'm not commenting on the flavor (which is great btw, but that just makes the class that much more of a trap for novice players).
After all, you give up a lot of what makes Bards awesome (spells and music) for slight numerical bonuses on situational stuff. The first level does strictly nothing that another level in Bard wouldn't give you, except for the slightly (ever so slightly!) altered chassis. After that, you trade two levels of spellcasting advancement for 2 skillpoints, the weakest feat ever (Alertness) and some bonuses vs. traps, which is never a good thing in comparison. You also lose all bardic music advancement to gain a bonus (not even immunity! cue Paladin scoffing) vs. fear.
Bottom line: you tried hard not to make it overpowered, so you managed to make it significantly weaker than a core Bard. Is that really what you wanted? If you get a little more adventurous with the class's abilities, you might come up with something a little more colorful, mechanically speaking. Low and situational numerical bonuses are not class features! Give the Arcane Explorer something to make him actually arcane and let him explore!
Why not some abilities like "lose a spell slot to become incorporeal for a round/spell level" or "lose a Bardic Music use to gain True Seeing for a round"? Why not something that goes with the "prestigious" exotic weapon you gain, like the Exotic Weapon Master tricks? Why not something to go with your Performance skills, which the class otherwise has no use for whatsoever? How about something to do with Explorer Lore (take a page from the Archivist's book)? I can also imagine some X-Ray vision powers, something along the lines of the Legend Lore spell, or maybe just some social benefits for being part of the Royal Explorer Corps.
Maybe even a mechanic which lets you choose (modelled via a period of dedicated research) a particular dungeon or adventure site as your personal grail quest, providing some bonuses or new abilities while you're about digging up that particular treasure/studying this particular creature/mapping this particular unknown stretch of countryside etc.
Everything but boring numerical bonuses which only apply so often!
EDIT: Only just saw the creation date of this long-dead thread, apologize for posting in it!
