Congrats!! That's awesome. Once you get that Light team's weapon grid up in level you should be able to use them to clear the other element GOs also.
Yes it's on the wiki, but it isn't spelled out clearly or on a main page. Even Sanhatlig's guide doesn't talk about it clearly. It took me a while to understand skill leveling myself when I first started.
Here you go:
https://kamihime-project.fandom.com/.../Weapon_Skills
Look under Leveling Weapon Skills.
Dejnov.