If you give your companion an armor set to hold onto that he/she cannot wear it just disappears. I went to The Fort and killed caesar. Gave the armor to Cass to hold on to and it said she cannot wear this fractions armor, thats fine. Fast travel to my house to store said armor and its not on her. Went back to the Fort and it was no where to be found.

I noticed when you give your companions armor they dont like, they throw it on the ground.