Ok so what's Keen?
It's said as an attribute or something as an upgrade for your lightsaber when you add some gem.
It's also an attribute for one of Chuundars Bowcaster's upgrades.
So what is it?
I'm guessing it's kinda good cuz the gem which has Keen is worth quite a bit of money...
"Keen" weapon is a wepon that has it's Critical Threat Range doubled. For example, a single-bladed lightsaber, that usualy has a Crit Range of 19-20, with a keen property has a threat range of 17-20.