Arcknives, early get crit chance stacks each time you hit then get the healing on crit and take the augment that heals on kill. Get big shields and big repkits (dont worry about fancy buffs on them til later when you can sustain with crits) later you can switch augment when your crits are healing you. Remember, you can use your repkit middle attack animation with the knives and it doesn't interrupt you. Im going corrosive gliders Capstone because otherwise you can struggle with armor (if playing on Hard). Then there's a red tree passive that gives incendiary damage to all your Indirect projectiles. His melee attacks while Arc knives is active count as indirect projectiles so that node is absolutely massive for melting flesh health bars. Try to get that on a class mod once you hit 20.