To clarify, I am referring to the first game, Secret of the Inner Sanctum.

I just noticed that my archer only has a Might of 9. Does this stat matter for the archer's damage? Can this stat be raised in game at some point? If so, by how many points?

Starting stats don't matter much in the long run, as you will find ways to increase them. But MM1 is not as extreme in this regard as later M&M games. Also, after 21 you need more and more stat point for them to give bonuses.

I'm pretty sure Might is not important to Archers.

Thank you Petrus

Yes, I believe the damage from Archers' bows is determined by Accuracy, not Might. So as long as you always shoot (which you should, since Archers can fire their bows even when inside melee range) you won't suffer from having low Might. It would only matter if you had your Archer try to attack with a melee weapon.