Dilapidate or Decrepify

Effect: Basic dexterity nuke on par with the potency of weaken at all levels. However, since the combination of the two would be particularly horrible against any melee class, I'd suggest that if they are both cast or communed upon a character, the second one will have a lesser effect.

So, if I am fighting a giant warrior and I cast decrepify first, I will drop his dex considerably. If I then realize that I should have cast weaken first, and then cast it upon him to make up for it, the spell's potency will be halved since the magic/power being utilized to achieve the affect is so similar. Basically, you gotta make it count, but it opens up some options.

As an additional tweak, it would make sense (and be cool) if this made movement a bit more taxing upon the victim for the duration.