I like to imagine this is a common occurrence for Ruby. Like she's helping Jaune build a customized weapon, and outside the door everybody is hearing:

"N-No. J-Jaune, You're-You're being too rough. You need to insert it…you need to insert i-it more….carefully."

"G-good. You finnaly found the right place, Now you need to….now you need to firmly press it. B-BUT DON'T PRESS IT TOO HARD!"

"W-We finnaly finished…..that was……that was TOTALLY AMAZING! I don't think i ever had this much fun with somebody else. LET'S DO IT AGAIN SOMEDAY!"

This sword shoots out stuff when used in a special way.