Okay, this is a real simple one that you can make out all the left over missile launcher arms you find in the Tactical box. Simply find a arm that pointed out. I used the a plasma pistol arm and cut it off at the wrist. Next I took the hand off that braces launcher. With a little glue...presto! Your battle psyker is doing the " I zap you...."
Time to put this project to rest and paint something cool. No offence to you marine fans.