Hmm, you must be taking about Ukast's Winterdeath. Well, the damage is only 5d6 (few would pay a 4 th. level spell slot for something dealing 5d6 points of damage). The Animate Dead effect is the same as the spell, so that could arguably be a lvl 5.
But, in accordance with the cost of scrolls / wands, it seems that spells increase rapidly in power as they increase in level, so it didn't seem unfair to make it a level 7 spell. After all, the spells it would have to be competing against in level 8 and 9... hmmm. Its already in the same category as Meteor Swarm and Limited Wish. I was thinking of making a Greater Winterdeath spell, that summons Wraiths instead of skeletons, making it a level 9 spell. Wouldn't be so good if the skeleton version was level 9 as well...
The reason I made it a level 7 spell for clerics, even though they have easier time Animating Dead, is that they normally have a harder time inflicting damage with their spells. So, it had to be high level just because of those 5d6 points of damage.
You ever make spells or magic items Kris? Or are you a creature-hugger kinda guy?