On the DC discussion, it's besides the point how high (or low) it is.
There will always be a failure on the roll of a one, always.
Nightmare took advantage of that in some way, a higher crit range on a weapon just meant your odds of the foe rolling a one would be reached sooner.
Now what's so bad about the change is if your wielding a Nightmare weapon at level (eg 21+, not including named items or prestige enhancements) all that you have going for is the mobs rolling a one. From level 16 and above most of the mobs are saving on a 2. That's why arcane arches get the fear effect on top of it, otherwise it just plain sucks (big time).
The only way a nightmare weapon would be overpowered if you take your level 25 character and drag it into a low/mid level quest and have him wield said item. The thing is, if your level is that much over the quest level and your relying on a nightmare weapon to do it's proc-ing there's something seriously wrong with your play style. Tho I do see a climbing trend in WF sorcs that wield a two wander.
