You need a LAW pistol (any level will do, its not for shooting) and a an Order shield. Then you can tank damage like crazy
(both blue level items)
Combine that with a high end health boosting relic (cooldown and melee dmg relics work well also) and you can tank a shitload of damage.
(law&order basically says that any melee damage you do with lalw gets absorbed back as health if you have order equipped)
Have you played the pirates DLC? there's a gun you get that gives you +200% melee damage. If you cant get law and order, that would be a good second bet, that and enough backstab and you'll never come out of deception till almost everyone is dead.
there's definitely a bit of a "dance" involved in meleeing guys, but I find the non badasses you can dance around and get in 6 solid hits on someone without them touching you.
I tried respecing mine as a sniper, but everytime a guy got close I wanted to run up and slice him.... only difference, he didn't die when I did this as a sniper! I had to go back to the melee build.