A/n up top is her new form for Alien X and make all of Yang's alien forms yellow like replace Way big's Red with Yellow and XRL8's Blue with yellow and so forth and she can go Ultimate and yes I know the omnitrix isn't technically a weapon but this one is ok and some of her alien forms will have different names
Yang was walking through the emerald forest with her boyfriend Liam and her sister Ruby until they saw a "meteor" drop right in front of them
Liam: GET DOWN! *sheilds them from it and is fine*
They get up and Yang goes into the pit to check it and sees a small yellow watch and goes to grab and it attaches and fuses its self with her right gauntlet and she flips out but Liam and Ruby went back because she said she was so they were no help and when she finished screaming she started to play with watch and she opened it up and she stares in awe and all the transformations until she picked one and hit (just imagine the Ben alien transformation but with Yang)
Yang: AAAAHHHH-*transforms into topaz* (just imagine this but Yellow)

Yang: WHOA what happened *accedently destroys stuff*
Timeskip to Ruby calling Ozpin about this and about this and Liam telling Yang to not use it
Liam: NO BAD
Yang: but-
Liam: NO
Yang hit it anyway

Liam face palms as Yang runs away
Liam: O_O
Yang kills some Grimm
Timeskip after Yang found out the rest of her current forms
Liam and Ruby finally calm Yang down and take her home