Weapon Damage#keep Changing

[(PSN)Nashun-15]

I cant get a accurate  damage count from weapons n da arsenal for example my akvastos do 407 damage but when i select another weapon&go back2da akvastos the damage is lowered drastically making me unsure about my total. it is really annoying when ur trying2pick da best weapon4certian game events or just2mow down bosses