Amulet with +4 to projectile skills

Hi there.
Just found a magic amulet with +3 to all projectile skills and rarity implicit. I want to desecrate it. I was thinking to aim at +1 to all skills. But:
1) is it even possible (none of such amulets on the market)?
2) is it worth it? maybe some other desecrated modifiers are better (?)
I'm playing Mortar Cannon Tactician so that theoretical +4 projectile would be nice, but I could also craft it just for sale. What's the most valuable desecrated modifier?

nevermind