just some assassinate ideas because nobody uses this skill atm

double damage against stunned target - this would be a pvp solution since it currently does lower dmg than a backstab .

make it be able to use out of stealth and increase the damage against targets below 25% hp. - making it a sort of 'execute' mechanism "assassinate" then maybe generate only 1 or 2 Combo Points. with a 6 second cooldown seems fair

make the target more vulnerable to other attacks after succesful assassinate

if used in stealth make u shadowstep behind ur target and maybe a 1 second root

i had more ideas but lost them , love hearing from the community.