Upgrade SA stage on a weapon

[TriHard]

It would be a good idea to put a mechanic that allows to upgrade the stage of a SA on a weapon. Some weapon have stage 6-7 SA which costs already adena but then if you want to make it lvl 8 you have to lose it all. It would be good that for a fee you can upgrade the stage of a SA and also while I am at it, we should be able to pay some fee to change SA without needing a new crystal because stage 8 is expansive. I think it would be faire to put a fee which is high but still much lower than the price of a new crystal just to change SA. Because if you want to buy a weapon and it doesn't have the SA you want it is very frustrating to know you need to change the SA and it's bad for peer 2 peer buy/sell of weapons.