Staffwrapping of [] Slaying

I've always wondered how the staffwrappings work.

Do they work on "wanding" ( normal attack ) or do they also work on skills?
Like if I have an Earth Staff of Ogreslaying, dmg +20% vs ogres and I use Obsidian Flame at 16 Earthmagic ( 118 dmg ) will it do 141,6 dmg ?

I expect it doesn't work on skills because it doesn't say "Damage +20% vs Ogres while using skills" but still

I don't think it would work with spells..only wanding...thus useless

It will only kick in on attacks from whatever weapon (in this case staff) it is attached to.