...finally got to the last post... and 2 more pop up, dammit. Bah, whatever - gadda say this - Guard is NOT dispelled by Dispel. Barrier is, not Guard. Guard is NOT a spell, it is not prone to magical disruption. Now some enemies may use abilities that do bonus dmg vs guard, or you can get stuff that does bonus dmg vs guard (such as KE Spirit Blade) but Dispel doesn't. It's also already been said but they didn't say the focus changes. Mike just said that all the skills would work regardless of weapon choices.
On the plus side, Dispels description states it removes hostile spells from friendlies, and beneficial ones from enemies so it's probably 100% FF safe (which it's pretty much always been in Dragon Age but you know, other games I can think of...).