And i think you whil be increse arsenal in time, steel i think its no harm to mention ather fun tool to delth whith heretics. 

Like: psyckostroke grenades(make random effects frome "non" to make enemys atack themselves), rad grenades(reduse max ammout of HP), psy grenades extrem demege to psycers and demons. Psy bolter munition (posibly as a weapon for hi level players  - same bolter(hevy bolter,autocanon, autogun, shutgun e.t.c. ) weapon whith psychic tempered and charged munition  whith signifintly incresed damage).

Psy cannon - salwo hi speed and armor penetretion heavy weapon.

Incenirator - imposble powerful flame trower. there is can be upgrede or modification of the weapon whith holly prometium(incresed damege). 

conversion beamer will be fun too - it have small damege frome near distens and almost ultimate on a far... probably it will have a sence to instal it on some armor. 

And yes simple grenade luncher whith drum magazin will be extreem fun too.XD

there is of cource a lot ather weapon i codexes and w40k background.