I'm telling you this as a White Mage... Slow is too strong, just wow. I tested this on Shadowlike the Rogue, hes using a quick weapon so he has maximum attack speed of 1 second... I use slow and it goes up to 3 seconds...isnt that the max ? So just casting that DRASTICALLY reduces his damage output, 2/3 of it gone.

How about instead, it doubles the Attack Delay penalty of your enemies weapon? This would make it less effective against fast weapons but extra effective against big slow weapons (although if they attack at 2 seconds, bumping that up to 3 is still less of a decrease)

Not sure what duration is, it says short. If it was 10 seconds, maybe.