This might sound like a really insane idea, but how about... making the chances for a UV on each weapon the same?
I know, this sh-...idea, yes, idea, just sounds bananas, but think about it: Why isn't it the same to begin with?
I am not talking about rising the general chance of all weapons, but about those few weapons that have never felt the tender embrace of UV love. Try getting an Unique Variant on a Troika and tell me how it was. That poor little thing doesn't even know where to put one.
As far as I know there are several such weapons. Do you not want to let them feel a purpose in life? To spend the night with them, alone, fill them with heat and have them reach the greatest heights?
Okey, after all these slippery innuendos, let me go deeper. Ha. Anyways, I do not see any valid reason for the chances of an UV on weapons to be arbitary. If any of you can tell me one, I am all ears. However, not the economy or the gameplay benefit from it, as the chances are not based on how popular or useful the weapons are.
An African or European swallow?
Getting UVs from crafting is already at a 10% probability. Do you mean to make it more likely to get certain kinds of UVs for different weapons?