A simple explanation would be that NQ elemental staves are Magic Accuracy+1 and Magic Damage +1, and HQ staves are 1.5 instead of 1. In other words, this is 4x as much of a boost to magic dmg as Jupiter's Staff, though the m.acc is only equal to Thunder Staff.
For damage +6 does that just mean it adds 6 to whatever your damage was? lol I haven't played in ages but this has always confused me, like haste +2 instead of 2%