Quote Originally Posted by peaches View Post
It increases your progress like Standard Synth but by a LOT more if you're crafting an item like the blackened smithy gloves that has an element with it.
Actually, it does the same as Standard Synth would do for an item of same level but not Vintage status. The vintage items reduce progress on non-elemental skills and non-correct-elemental skills by half. But yeah, you would want all of them and equip the right one if you want to finish vintage items comfortably.