Description: When using the Unit Designer you can click on an existing unit and select "Upgrade" which loads the current unit into the Designer and you can adjust that units equipment from there.

However you're not really "upgrading" that unit, you're creating a new unit based off of that design.

That's a very useful function to have, since it will save time when you gain the ability to create newer items and you want your troops to have them, but your existing units based on the original design aren't "upgraded" to the newer equipment, it's just creating a new unit type you can recruit.

I'm not too sure what to label that button instead to make it more intuitive.

Suggestion: Remove "Upgrade" from that screen entirely and simply have the "New" button use the existing unit as a base instead of the current semi-randomised default?