Sorry, it's Victor Engine, not Galv.
It's all good, simple mistake.
...did you type into Google "RPG Maker Ramza dual wield"? Because the top results for me are his release thread here and the product page on Itch.
...Maybe I forgot to look. I'll do that in a bit.
I think you should be able to do it using Yanfly's Equip Requirements, using the Custom Equip Requirement notetag and some JavaScript checks, but that requires coding and isn't free.
While it isn't free, I was able to get the plugins through Yanfly's ******* for only $5.40USD, even though the work they did deserves the full $30 from their itchio. Even so, I don't think the Equip Requirement does what I'm looking for, but instead restricts equipping an item at all based on certain actor parameters. I'll look into the Victor Engine and Ramza plugins and see if they line up better with what I'm looking for.
EDIT: Ah, I see. Yeah, the Ramza plugin is like $15, which is why I didn't fool with it much.
EDIT2: Yeah, looks like the Victor Engine plugin just falls short of what I need, putting both weapons on one attack slot, making them both attack.