If you execute a dodge when the troll swings he'll miss you. Even with low bow skill you can draw and fire an arrow before the troll can swing again. If you see a troll approaching your base get his attention and lead him away. He'll attack you in preference to attacking your base.

Trolls are weak to piercing damage so use weapons that do piercing damage like the bow and atgeir. The atgeir has cleave so it does full damage to each target when you hit multiple targets. The only down side is that using the special attack burns a lot of stamina but you can retreat in a zig zag, when the troll swings you dodge and then use the atgeir's special attack which staggers the troll and the greydwarves and while they are staggered you continue walking backwards to regain stamina (you can back up in a circular pattern too). repeat until every thing is gone.