I think thieves should be given an ability that's similar to Rage, but rather than increasing strength and decreasing dexterity it would increase dexterity and reduce strength. Thus thieves would have a defensive ability (aside from Covert if you want to consider it as such), but the added defense would come at the expense of the thief's ability to fight.
When you use the ability you'd get a message that's something like, "You tense your muscles, preparing to react to incoming blows with lightning speed." I know the description is pretty weak... if you have something better, by all means post it. While under the effect of Tense your dexterity is increased by three, and your strength is reduced by five. The stat mods remain until you turn Tense off, as you do with Rage.
Any thoughts?
Edit(s): Changed the phrasing a bit.
Edited by Kharybdis, 25 February 2004 - 12:10 AM.