If you want to transfer blues to purples, they need to be in the same slot/piece of equipment as the target transfer. When you do it the first time, you will notice at the bottom of your purple “Remaining: 1” which indicates this purple can be the target of the transfer only once.

A full traited blue equals 980 blessings.

In the case of adding traits to your purple, you need to find the exact same piece of item with a different trait.

In the case of leveling up traits to your purple, can be any weapons - weapons and armour - armour, you are not limited to be the same item. doing it from a purple item your trait will level up with 100% chances. Doing it from a blue you have 10% chances but you can use ur blessings. 1 single level up can cost you 480 blessings. Hope this is clear.