Itemization

[Lissa]

That implies that there is some sort of multiplicative effect. Other than the weapon speed (a stat independent of DPS) serving as a multiplier for instant attacks, there isn't a multiplicative effect with weapon stats and attack power dps.

When a warrior has a 40dps 1h, they likely are getting ~60 dps from attack power. So 100dps regular attack damage. getting a 50 dps weapon with no change to attack power takes them to 110 dps regular swing damage, a 10% improvement, not the 25% improvement it would appear to be at face value.
[right][snapback]88909[/snapback][/right]

The thing is, the stat boosts that you see on the class sets for the Warriors and Rogues gives that boost to MAP which in turn gives a boost to DPS. Casters don't have anything like that.

One of the suggestions I saw on the Blizzard boards to actually make Spirit more interesting and useful for Casters was to give a +1 damage/healing boost per x amount of spirit (someone was saying someting like 1 damage/healing per 5 to 10 points of spirit). This alone would go along way to making people seriously considering Spirit again and it would make it a useful stats for Warlocks and Mages (at present, there is absolutely no reason for Warlocks to have spirit and little reason for Mages to have it).