The blade can be handed over to none Lightforge family also. But if it touches the flesh of one who's not fully devoted to the light then it will shatter and render usless. There's only one other's hands that Vladimer knows he can wield it for the time being.
For now it does infact resign in Vladimer's presence. He keeps it disguised as a common Lord's sword of steel for which it woun't drag attention. Only him, and the other one who's worthy enough, can reveal its true form.