Description says it prevents skill use...

but how does it work? Does equipping it make all your attacks seal the enemy skills? I never see it activate.

It means that the enemy can't use special attacks/magic on a character with "Seal" equipped. They can only attack with the standard attack of their weapon.

Not sure if it also applies to passive skills like "Manhunter", though.

It doesn't work all the time though. Chances.

My Elizasleyn won't seal those special moves all the time. Guess I need to test it later.

Seal works on *magic* attacks and that's the key. It's not Forcefield which works on everything ranged. If you're getting slammed by Barrages, Snipes and stuff that's intended.

I'd post a reply back if you get hit by a Sunlight Burst or something because then you'd have a problem with it only occasionally working.

Tried, and yeap. My fault for not paying attention to what attack the mob is using, since I don't usually care.