A few thoughts...
This falls along the same lines as blind, which, for a very small cost, is probably twice to three times as disarming as any level of skill in pkill.
I've thought about these problems a great deal, and I'm not sure exactly which road to take as a solution. Even a spell that decreased con, strength, dex, isn't as debilitating to the fight system as is one the decreases mind over the boundaries of skill qualifications. I'm pondering a couple solutions to this problem, and as soon as I have the chance to talk with Ea! and a few other coders over the situation, I'll post some of my ideas and see how they float.
As far as parry, I'd personally like to keep this as a skill that is available to all, perhaps making med/london hometowns better at it than ancient, but not completely taking it away, seeing as the arts of fencing were really given a boost in those time periods.
Again, I would just like to state, I don't think it's necessarily the mind req that's the problem, it is how easily so many skills are lost over a very very common spell.
Or, we could give it a bind-like twist so that mind comes into play AND a chance to simply randomly backfire. I think the same should be done to idiocy, as those spells are rather destructive to fighters.
However, with the recent downgrade (sure as hell fe like it) of tumble, fighter chars have become rather effective if not nearly as effective/more so than dedicated mage characters. Hadnt i unclanned my past clanned, i'd even go as far as to say that he'd be much more a force to be reckoned with than my current clanned (somehow, of course, tumble's effect -iveness dropped as soon as i changed pk chars, but i am not that egotistical to think that i caused the change ;)
Got a bit carried away, but the point i am trying to make is that sure, those spells are overpowered and leaves almost no option to fighters other than renting those effects out, but as mages are starting to become weaklings relying on spells to win (before they were just dex chars with tons of hps) i think the current system isn't truly that harsh to all fighter types.
I did notice tho, that perc chars are seriously suffering, and suggest that more bonuses be given to perc. Perc chars are roughly in the same boat as mages are in terms of stat balance (without the benefit of having spells) and receive benefits that depend on luck at best. It would be interesting to giva perc skill that's anti-choke/kick/elbow, with even greater bonus added to tumble, so they have more a chance to actually win without counting on snipes/paralyzes. As of now, snipers are probably one of the easiest char types to kill barring a snipe/paralyze. (especially for a 3rd cause).
Well, enough rambling.
of course, then you'd have to deal with spell levels and the like for people and maybe that's not so good.