There is a good reason this spell is not on the Duskblade list. I disagree with you that a fighter mage could take more advantage. That is patently false. One of the primary reasons I think the spell is fine is because you have to split so many levels between a fighter and a mage, thus reducing the characters overall effectiveness in order to get to 10th level where the combo starts to pay off. Such balancing factors are not present with a Duskblade, that has both classes essentially present at once. To claim this spell is broken because you wanted it with a type of class that is expressly not supposed to get it doesn't help this debate in my mind, it just clouds issues even further.
You think Duskblades with Wraithstrike are common?
You mean, like the rules as written for a Duskblade?
I disagree, and from what I can tell you have never even bothered to try the spell out with the characters that have it on their spell list to find out for yourself. That's a shame, since you've heard from two people who think it is fine, and several who think it is not, and obviously experience plays a role in this issue.
MAD, in a D&D context, is multiple attribute dependency, something these builds suffer GREATLY from. It's again one of the built in balancing factors for these builds.
MAD in a political context was both countries already having them, not one wanting them. If one has them and one does not, that's called SAD...single-assured-destruction.
Usually not. Usually, if one has it, the other is prevented from getting it.
But you have never seen it by your own admission. This is theoretical to you. In my actual experience, it doesn't happen that way. In some other people's experiences, it has. So you should try it in your game before you conclude on paper that such is the case.
No. I'm trying to convince you to try the spell in your game and see how it goes, and not come up with senarios where it is balanced that get whacked down as being hasty generalizations, and then whacky down other people's single examples as being hasty generalizations.
It is extremely difficult to convince a D&D player in a rules forum who has publicly entrenched on a position that they are wrong. Your own experience will be much more persuasive than anything I say here. So try it. What are you afraid of?