what does the power part of items do?

what does the power part of items do? i can't seem to figure it out. if an item gives me me +90 power or + 30 i cant tell the difference. does it effect how hard you hit? i would realy like to know

Power appears to have two impacts, depending on what it is. Note that this is from observation rather than looking at the code.

For a normal item the power is how much mod ID you need to be able to identify it. Higher power needs higher ID spell. Power does not affect the performance of a normal item in any way that I have observed.

For a spell scroll the power is the mod power of the spell it casts. Higher power then the stronger the spell.