I'd be really pissed if my partner gave away one of my sex toys without my permission, and added insult to injury by watching sex videos of the other person using it.
And I'd be totally grossed out if someone GAVE ME another person's used sex-toy (even if it was sterilized in an autoclave first). Couldn't he have bought her one on Amazon and had it shipped to her if it was that important that he give her that kind of present?
It's just creepy. It's like if he took your used underwear and sold it on eBay, or something. No, it isn't EXACTLY the same thing, but it is the same creep-factor because it was done without your knowledge or consent.