I'm a fighter archer, just turning level 4. In my last session I rolled double 00's for loot and was rewarded with a +4 composite longbow of thundering. I'm pretty freaking stoked. I plan on taking improved critical as soon as possible, but I was wondering if there are any other ways to increase my critical threat range? I'm sure folks here know a LOT more than I would.
I can probably use some third party sources but nothing too far in left field. Unfortunately you cannot apply keen to a bow and keen edge on arrows will not stack with improved critical.