So, actually, it seems like it was an OK encounters. Chances were she'd never have beaten them, but you probably didn't want that anyway. She got two rounds of action, which included being fairly unlucky. Had she hit someone with Colour Spray, odds are Mr Skelly would have lasted another round. She probably would have gotten a third round in then, especially if her R2 action also took out some party members (e.g. Glitterdust). At that level, buffed with Mage Armour, there's not even a guarantee that they're hit her with any reliability (what, +1 BAB, +3 Str vs +2 Dex +4 AC, say... maybe +4 Str +1 MW or whatever, it's still about evens at best) so she could easily have caused more hassle for them.
The flip side is that she could have gotten very lucky. Colour Spray could have knocked them both out, making them vulnerable to Mr Skelly. He might've died to the other party members, but then she could have hit them both with something. You could easily be looking at 1-2 deaths or more at this level.
I don't see really what the problem is. Maybe you could've built or played her a bit better, but know you know for next time, and to be honest who cares? The encounter may not have been particularly challenging, but it wasn't without threat, and the players just got luckier than they might. Either way, it certainly sounds more interesting than yet another Gnoll Fighter.