I don't think your rogue quite grasps the assassin concept. Firstly, I'd wager that the majority of assassinations would be against high ranking mucky-mucks with an approximate "level" of zero. This is basically equivalent to being a minion.
Secondly, traditional assassins are sneaky-types that like to sneak up on people while they're defenseless and probably unconsious. If my target were in such a condition, then I should be able to one-hit kill them. Fighting someone who is both awake, aware, and likely armed, is *not* going to go down in one hit.
I'd suggest throwing some skill-based encounters in which hears about a corrupt government official, and has to track down his residence, sneak past a bunch of guards, and off him while he's napping. Were I an assassin-type, I'd be excited about something like this.
Secondly, traditional assassins are sneaky-types that like to sneak up on people while they're defenseless and probably unconsious. If my target were in such a condition, then I should be able to one-hit kill them. Fighting someone who is both awake, aware, and likely armed, is *not* going to go down in one hit.
I'd suggest throwing some skill-based encounters in which hears about a corrupt government official, and has to track down his residence, sneak past a bunch of guards, and off him while he's napping. Were I an assassin-type, I'd be excited about something like this.