@floodtalon On the subject of stealing my mech.
That is a thing you can do. And how has been established.
Miyu's mech is so closely associated with her that it respawns with her if the Nexus respawns her.
As Gwynn's death leaving behind her sword, halberd, shield, and armor means, if you killed Miyu while leaving her mech intact, and the Nexus didn't respawn her, you'd have Miyu's mech. Not sure how you'd manage that, but hey, it's a way.
If you wanted to side mission, you could infiltrate Miyu's home base, and steal one of her back up suits that she has for situations where her mech is damaged/blown up and she needs a different one and doesn't want to/doesn't have the time to commit suicide and trust the Nexus to respawn her and it. You could also blow up her mech, wait for her to come back in a back up suit she hadn't attuned to as strongly as the current one, kill her, and have that one.
You could also steal her mech by capturing/knocking her unconscious/teleporting her out of it, and not killing her. As Miyu doesn't trust the Nexus resurrection very much (and after the Angelic high command fiasco, she shouldn't :P), she'd be loathe to kill herself to respawn back with it.
Considering our relative power levels and the power levels of our friends, what with you having the silver eyes and knowing Victoire, it should be possible for you to manage one of these, with or without my permission.
Of course, if just a power boost is what you want, and not just Miyu's mech because it's Miyu's, you could totally just steal mechs straight from Machina NPCs. The Daimyo V is not meant to be a super special awesome unique prototype weapon. And if I ever get the chance, I'm totally gonna rip some rocket barrage thing or giant laser guns off Machina NPCs to temp power up.