What do ultimate boosters do?

I just got a few of these in the ultimate quests and was wondering what you use them for.

in the moment they do nothing, later they gonna be used for certain weapons

They do do something already, they can be used to unlock a stronger version of the current 14* weapon latents... if you have any of them that is. These stronger latents are also balanced around Episode 6 content.

As of Episode 5, they also can be used to make the "Protection of Friendship" Right Ring. This reduces damage taken. (It also needs 20 Pure Photons.)