@Ibri
Seems like we can agree on the fact that they're both dumb excuses, I just prefer the less contrived one (less weight = faster) because it's simple and has a minimal impact on the world building. Is it an effective way to gear up for combat? No it's not, you're right but the statement that it does make her faster/more agile is still true so it's a simple excuse that needs no further explanation.
If you're adding force fields just as an excuse to have someone wear slutty armor, that's now a completely new 'mechanic' added to the world that will change how people fight and equip themselves. It's a lot of writing effort that will go into this and if its only purpose is to be an excuse, that's wasted effort.