This is a book I read as a child, so sometime in the 1980's . It was actually a two part book series, both normal novel length. It was a swords and sorcery style setting.
Details are sketchy, but I'll give you what I can remember.
It centred around a boy on a quest against some demon-like villain wizard type character. At some stage a girl was kidnapped and they were off to rescue her ( fairly generic stuff) . I think the girl also had magic powers, healing I think.
This boy could control the weather or elements. He encounters a monk type character who ends up travelling with him and becomes a teacher of sorts. This monk is actually blind, but can still sense his surroundings, DareDevil style. ( I cannot remember if this was a magical ability or just something the monk had developed over time. ). I seem to remember this character had black, reptilian style eyes. There may have been more people travelling with them I don't recall.
I recall the encounter with the main enemy took place on the top of a mountain, this mountain had the top taken off so was perfectly flat. ( I hope I'm not getting muddled with a different book with this detail)
The baddie know the boy could only control the elements if he was exposed to them, so ended up sealing the room he was fighting in so the boy had no contact with the outside. He won through by using a dagger or sword to make a crack in the floor through the protection, giving him enough of a connection with the outside to use his powers. I /think/ he died during this battle, and the girl they were rescuing brought him back to life. ( Or maybe she dies, and was brought back to life somehow)