Okay a few mistakes you've made there Surrealistik.

Firstly, acro-flagellants have unnatural strength and toughness, meaning damage reducing is 11 points (3 armour + 8 for toughness) and the float power being only 5 feet off the ground? For a strength bonus of 8, thats a piece of cake to jump and swing at.

Secondly you've suggested that if the psyker can have a MP Lascannon AND be able to carry it along with all his other gear, oh so subtlely, the comely unoptimized assassin would atleast have a heavy bolter by now.

Given that hes still outperforming the psyker on raw damage. Given his bonus +2 damage and the heavy bolter on default outdamaging each force bolt, hell if he wanted to he could get in a little closer and get a +30, meaning garunteed hit.