: Being a warrior or common soldier makes the most sense.
: He hints that he is a fighter of some sort, but he
: never really meets with any important figures, or says
: anything notable about his past.
However, the majority of the game's levels (two before Madrigal, all of them after Madrigal) have no warriors, nor any melee except Trow, Zerks and Heron Guards (which the narrator obviously ain't). It's one thing to have a level or two which don't feature a unit who, according to the narrator, should be there (e.g. Garrick and a squad of Warriors should appear on Beyond the Cloudspine); it's another to have the narrator's unit absent for more than half the game. Unless the narrator switches bodies at will, I think he pretty much has to be an archer.
: It might be possible that he is a common archer, that
: would explain the fact that he is alive, but he was
: not trained in the Ermine. Not all archers were
: trained there, so it is possible that he just sat back
: with other archer brigades and did his job while
: observing....
This would also explain why he's interested in joining the Heron Guard. Having been trained by the Legion rather than the fir'Bolg, he'd have learned a lot more about melee combat to complement his unexceptional archery skills, and so it'd be more plausible that he could become a katana-swinging Heron than it would be for one of his more specialized fellows.
--SiliconDream