If this is "your friend's" aunt, I am guessing she is your friends mother or father's sister. That the guns and knives belonged to your friends mother or father's parent. Your friends grandparent.
This sorted out, rather than your friend going over to take the items, why not have the aunts sibling (your friends mother or father) go and liberate the items for him?
If my sister were living in my parents house with their belongings after my parents were gone and my son wanted something from his grandfather, I would go get it for him weather my sister liked it or not (she would give me anything she has for the asking, this is hypothetical). I wouldn't want him going and helping himself (unless I was dead). My $.02
This sorted out, rather than your friend going over to take the items, why not have the aunts sibling (your friends mother or father) go and liberate the items for him?
If my sister were living in my parents house with their belongings after my parents were gone and my son wanted something from his grandfather, I would go get it for him weather my sister liked it or not (she would give me anything she has for the asking, this is hypothetical). I wouldn't want him going and helping himself (unless I was dead). My $.02