does telekenetic weapon count as a weapon for the purposes of legacy weapons?

As in elevating a telekinetic weapon to a legacy weapon?

as in useing the psyker power Teleklenetic weapon while he has a force sword as his legacy weapon

As it is a power, even though it technically manifests itself as a weapon, I'd say it doesn't count as a weapon for the purposes of a legacy weapon.

yeah that was my ruling too

I'm sorry but I disagree with this. I will agree that the psyker is using a power. But that power is creating a weapon. The only difference between TK-weapon and a normal one is that the TK weapon will go away if the user is denied the opportunity to sustain it (unconscious, stunned, etc). Otherwise, the TK weapon uses the WS characteristic to determine hitting or missing, it can be parried, and uses the Strength characteristic to determine additional damage.

Legacy weapons are meant to be the one-and-only weapon and presents a very limiting effect for all the extras (additional traits, damage and pen grow with the wielder, etc) that are afforded to it. Hence the penalties for using a different weapon while possessing a Legacy weapon. Unless circumstances dictate that the Legacy weapon has ZERO chance of being useful, then using a different weapon will cause the Legacy item to revert to a normal weapon.

This is not to say that a psyker cannot use any other damaging psychic powers (Doombolt, Force Bolt, Force Storm, etc) while also wielding the Legacy weapon, as the mechanic for determining success is different.