Two words: Liquid bandage.
IDK what your level of gi BJJ experience is, so it's hard for me to contextualize what you're doing in your training in that area.
Ya, I've been using it on this cut I have on the palm of my hand but it still got torn open. I don't really want to use it on my knuckles because it's just a bit of raw skin and will probably crack when I bend my fingers.
I'm a large strong rusty blue belt. =)