I read this book sometime between 2000 and 2009 but can't truthfully say if it was new at that time. Fantasy world in the usual Medieval village tech level setting.
Most people have a power which manifests around puberty. Some are pyrokinetic. Others are known as "swifts" as they can, for a short time, be as quick as the Flash.
Yet another type are "invulnerables"because their injuries recover very very quickly and they spend most of their life smashing their fists against rocks to give themselves two solid weapons. . There is (I can't remember why) a conflict between two towns.
Swifts on both sides are zipping around the battlefield hitting with clubs. Invulnerable are battering at each other and whichever enemy crosses their path. The pyro ones are criss crossing heat beams and trying to incinerate opponents.
The military turns up on horseback to stop this, the " Light Brigade ", they too are pyro's but very high level adepts and after a few well placed beams they begin restoring order and stacking the charred bodies
That's all I got for this book
P.S. there may well (and probably were) other traits/powers as well but the only three I remember are mentioned above