Mastercraft(MC) and Godcraft(GC) are usually on weapons and armours. They can help you to increase your statics. e.g. +3 reloading +6 critical hits ETC. MCs and GCs weapons and armours usually are sold in high price so I strongly recommend buying those weapons and armours if you had enough money.

WRANING: Don't get rip-off by other players for selling weapons and armours that are MC and GC in very high price. e.g. M24 sniper rifle MC sold price-$100000 original price $5000 for MC.

Sometimes MC and GC weapons and armours can be found by looting. But very low chance.

MC= + any number for weapons at 8 or below.e.g +8, +7, +1 for either accuracy, reloading or critical, or can be all. Armour e.g +10, +20
GC=+8 for Accuracy, reloading and critical MAX for weapons, +24 for Endurance and Agility for armour