Hello, it is easier to change certain skills instead of changing all staves to +8.
For PvE related reason: lower the skill damage %
For PvP related reason: lower the skill attack power
Attack power is more pvp based, because players will use a high absorption/def compared to mobs. Attack power is simply calculated by char attack power + skill attack power, thus lowering skill attack power will cause a similar effect to decreasing weapon attack power (or enchant level). You can also change life turnover stats if that buff is causing your problem.
Or: Decrease the overall raw damage output.