yeah smaller powers would be good, thoug hthe big warp blast os what the weirdboy is all about - puking a stream of psychic energy!
and id say a perils of the warp attack that kills the weirdboy is a headbang = place ordinance template over the psyker. all models under template take a str2 hit +1 str/type of psychic attack that was used. Ap6 (enough to take out a normal ork boy without need for a save
)
also they weirdboys have minders which are just bodyguards designed to keep them safe from the enemy and to stop them wandering off on their own!