I haven't investigated, but I THINK it's only for select few SSR weapons. Where you Limit Break their Limit Break limit. Yo dawg, we heard that you like Limit Breaks in your Limit Breaks, etc. It's kinda like Awakening, except for weapons. And costs Dragon Eyes?

Again, don't take my word for it. I have NOT looked into it properly AT ALL. It's not something we'll have for the next 11 months or so.