In my last, and as it turned out failed, catch-em-all playthrough, I spent several weeks trying to obtain the belt doing nothing but studying at school and diving. Just saying. It is not easy to get, unless RNG god is willing to screw you over with a belt that is twice (could be even more, I'm too lazy to go check the wiki) as durable as the regular one.
I once proposed an idea to give a key to Winter to once, and only once, remove the belt, maybe with a higher chance of finding it for a second time, but now that I think about it, it is probably fine the way it is. However, Vrel could come up with an alternative to just breaking the belt in the future, like a special event given by some befriended NPC, we can never know.