I'm looking for a heroic fantasy novel where the main character has to fight giants of different sizes and strengths in order to stop the great evil (maybe a super powered or magic-capable storm giant?). A key plot element was the main character discovering the ability to use a special kind of breathing to grow in size so he can take on the giants. I also seem to remember individualized weapons (an axe?) playing a major role. Read this late 90s-2000, although it may have been published earlier. Any ideas what this might be?