Board Thread:Off Topic/@comment-25343309-20150328012833/@comment-26018514-20150411074028

it sounds too much like a "grimm" arm for me to support...because of the following options for what you have described; However if it is able to be attached in such a way that his body then keeps it alive(or controls it) it seems like it should possess at least a big enough break in the seal that the trapped soul within moved on/died and thus the wielder loses the secondary semblance they gain that gives the arm powers fairly quickly...
 * We've established on previous threads about this subject that grimm bodyparts/fusions are a bad idea.
 * Demons don't seem to exist in remnant.....
 * The last(arguably best) option for what you have described is some kind of ritually sealed soul/aura inside the arm the user is then able to use...