Lance Usage.

So I just tested fighting while mounted with commerce partner with a fixed xml, it still didn't let me fight with her on my back. (And it took away her running animation since its not defined for every female human.) So it's probably not a mod that caused your friend's abilities. Can you ask if you can see them do it first hand?

Not defined for every female human??! What?

By that I mean, you can't just make a 17 year old female human and get Commerce Partner's running animation since the server and animation.anievent(?) hasn't set normal females to use that animation over the regular running animations. So most of commerce partner's nongesture animations should stop working if you were to modify the files, unless you wait for a fix on NA's part to finish the menma AI server-sided. But the point is, changing her defined species type didn't allow people to fight while mounted, since Godwrath1 knows people who have been able to do that.

Completely lost, but don't really care about the subject of commerce partners. :c

Modding racedb.xml, as you said, does fix the weapon/shield glitch. But it doesn't let you fight while she's on your back and it robs her of her special running animation.

Thats just the thing. I have seen them do it first hand. I have been talking to the guy i saw do it and he claims that he can't. I came to the conclusion that when I saw him using combat skills with her on his back that it must have been due to some kind of lag. We ran a tests while running dungeons and it seems that this event only occurs while the commerce partner is dual wielding. It seems that her dismount animation gets stuck. We were able to recreate the event only once and it had to do with a dual wielding partner dismounting, then him immediately using windmill. But like I said we could only make it happen once so that might not be what caused it. IF anyone else can recreate it some other way please let me know.