They give a variety of bonus, but not all do damage bonuses. The crystal orb is +1 vs Will and +2 to psychic damage (only). Yes, telepathic psions love it (but not telekenetic ones).
The ones that give damage bonus are not feat bonuses, so Weapon Focus + Superior Impelement stack with staff's/daggers. So a telekenetic psion with a Weapon Focus'd guardian staff will do +3 to damage with force powers (+1 to all else).
Broken? Consider that the damage/accuracy/special properties bonus are to try to match the damage/accuracy/special properties weapon fighters can get from superior weapons. The question is do they match up?