If it is not a naturally stabilized wood, such as those posted above, use a deep sealing coat first (after the handle is fully fashioned and ready for finish). For example: mix mineral spirits with Tung oil (about 3 to 1 in favor of mineral spirits). brush on liberally and let it soak deep into the wood. After curing, at least 24 hours, a second sealer can be applied and it can be heavier - say 2 to 1.
Roger