LiaThistle
It depends on what you're going for, I'd think.
If you have long descriptions, then the battle will seem more of a grand massacre/field/whatever you describe. If you have short, staccato sentences, it'll heighten emotion and the feeling of urgency.
You should pick which one works best for your goal.
Edit: Leaving out details is perfectly fine. Not everyone is super observant, and if you're trying to go for the higher emotional response, then it's better to not have sentences drag on with details about "he executed a parry 5 to block the head assault, then, with a bit of a push, threw the opponent's sword out of the way long enough for a simple slash."
Agreed. I'm fond of focusing on the characters, their thoughts and emotions, and such over a blow by blow, for example. It all depends on what's important. Like most things in writing, it's a mix between too much and too little. It's all a balancing act that you can only know where the balancing point is by writing it.