Ability to put basic directional shields on Primary attack, similar to the ones they can put with one of their Abilities, with some additional resource limiting amount of those (replenishable charges) and possibly them being less durable than the ones created with the Ability
On Secondary it would apply mass stagger in a short cone in front of them, similar to Arbitrator’s shield or the Shriek ability - scaling with the charging time. On max charge it would be enough to drop chaff and push away human-sized elites and light-stagger ogryns.
So a pure-utility staff, if you wish to sacrifice your range weapon for that.
Weapons that offer utilities would be difficult to balance, either it end up being too weak, or over present.
Keeping the shield in the Abilities is good enough. Psyker need staves (or other ranged Psychic weapons, either as mediums or separate/specific stuff) but those should be treated as weapons.
This idea is actually really cool. I’m not as on board with the secondary. But the primary basically being a deflector block is sweet. Honestly it should function as just a block that can block ranged attacks as well because of the additional blocking talents on psyker. Such as the perk that makes you gain peril instead of losing stamina. I would love this ability and it would offer almost like a mini-bubble/wall on melee psyker for more survivability from gunners. Good idea.