Voidfang: -you get more special ammo, just like with Armamentarium. -additional seeker means more damage output, also if you spawn everytime with full grenade, that's kinda close but I agree not the same Praxic fire: -you get more heavy ammo -all abilities cooldown faster, you just have to kill. So yeah a titan spawns with 2 grenades, but after use he has to regenerate them, which is a lot of time for two, I think with the praise the sun ability you can down your cooldown for grenades to get grenades muck quicker, ergo resulting in approx. the same amount of grenade usage