Mana burn is an absolute must. As a specialized assassin class, if you can't terminate your target within stun/disable times then you're as good as dead yourself. Those two extra seconds could be another demolition tick without detox, two seconds to run away if you're losing, or even a whole other pp under trap to get the kill.
I feel like you have a lot of unnecessary awkwardness in there. Level 1 skills tend to be bad to have unless they max out at level 1.
Death blow is bad, and Sudden Attack really doesn't do anything at the higher levels. It scales poorly because if you think about it you might still be a low level/new player at level 30, but keep in mind that's nearly 1/3 of 99.
With the rest, I'd consult another persons' guide. I'm not an expert on predators and I don't want to send you in the wrong direction.