Trolls are weak to piercing damage so as most of the above - arrows. Flint and feathers are pretty easy to come by as is resin so crafting flint or flaming arrows will save you a few shots. Flaming arrows apply a slow DOT and the DOT from fire arrows don't stack so to maximize your damage you have to hit with a flaming arrow and then wait until it burns out to fire another.

Trolls resist blunt damage so clubs or a mace should be avoided for fighting trolls. Once you have enough bronze to make a bronze buckler you can effectively parry block a (non-starred) troll and then get in 3 quick shots with a one handed slashing weapon (the third swing in a combo attack should do double damage). That will take a troll down faster than shooting it with a bow especially when your archery skill is low and it takes a long time to draw.