The difference between Wugushi 2 and Sapper 2;
Wugushi 2 - Small AoE with pot, but has poison pot mechanic to save you weight/space. Poison pot mechanic means you either have to buy poison from the Master or get insect mob drops, and store it in the Poison pot to be used later. 1 poison from the Master costs 800 silver and fills up to 400 poison pot poison. You use 8 for the AoE. Majority of skills are useful.
Sapper 2 - Larger AoE with Broom Trap, but everything else is quite bad. Takes up quite a bit of space/weight since 1 Broom Trap = 3 Ash Wood. 1 Wood = 1 Weight and the Sapper Master is a dork who doesn’t stock the right wood.
Take Wugushi if you like Poison or if you feel like you need more skills that will attack bosses while you run around. Otherwise, Sapper 2 for the larger AoE that has consistent damage. (In CBT2, the damage is spread evenly among the mobs in the AoE. So, more mobs hit = less damage per tick. Could have been changed but unlikely.)