There are a lot of ways to play the game so don't worry! Later on you can also re-spec your skills.
Bow are good but don't dismiss the crossbow! With a 10%+ to crit chance if you put one point in crossbow skills and relatively higher damage, they are pretty solid. Downsides is the movement penalty and 5 AP per shot. It tends to make the marksman skills stronger though since they are a function of your weapons base damage.
Dual-wield is great since at about rank 4 you basically get one 'free' weapon attack. 3 AP for 2 attacks? Great for de-buffs from "chance on-hit effects" or hoping to get that critical hit (since some weapons have a natural crit chance bonus, you can get 2 of them for a moderate chance to crit hit)!
I've never really tried maxing out single weapon but maybe that plus shield specialization can work.
As an aside, the poison slug summon (geomancer level 4) is probably one of the tankiest summons I have seen. It actually SURVIVED a destroy summon spell cast by the enemy. Bad part is it leaves puddles of poison all over so it could be rough for your melee. You can try using a spear since you actually can attack further away to avoid puddles.
Anyways, you can usually fill out any weaknesses with magic to do crowd control or summons. The game is pretty flexible.
