Landing both strikes can be quite unreliable in pk. That's how close it was.

Also, you may have been wearing a lot of +hp gear, but you weren't using any other protections as far as I can tell.

At your level, as an evil conjie, there are a number of protections readily available to you, including haste and protection. Had you used a weapon that parries better than a whip you would have forced the paladin to retreat at the least.

That wasn't a class mismatch. That was the paladin getting "lucky". However, he only lived long enough to "get lucky" because he did pretty much everything right.

PS: Two handed dedicants can tank well too.