Im having a hard time getting the Scoundrel to be a useful party of the party.

Im using Wolgraff and struggling badly with him. I just attempted to backstab a goblin mystic, got 2 hits in and only did about 30% of his life. The mystic turned around and killed him.

He is level 13, with two level 12 purple weapons. I mistakenly took sneak lvl3 and guerilla before reading and realizing how bad sneak is. My Scoundrel is at 5, and DW at 3, dex at 11 percep at 12.

Any help would be appreciated. Thanks!