Difficult to say really given that Ike is a mortal thrall (servant) of a Highest whilst Nyr actually IS one, albeit a small and comparatively weak one. My thought is that the weapon would be invested with some of Ike's master's Mass...though of course that's up to Chad. If so, the projectiles would hurt Nyr and cause some damage, though I think nothing overly-serious...Nyr will probably try to get away and pull Mar along with him so that he can attempt to rip the tendrils of foreign Mass out of Mar's Mass, in an effort to honor Mar's wishes. However, if Chad wants the weapon to do serious damage to Nyr, Nyr will treat it as a threat and will not hesitate in defending himself using whatever means necessary or convenient, regardless of Mar's feelings on the matter. After all, deals are no good for the dead...at least not in the case of a Highest, eh?