I read this book back in middle school (about 1998-2000), and remember very little about the plot. What I do remember is this:
- The main character is a young man who leaves his farm on a quest for a magical something or other. His only weapon is a knife that he had forged from his gardening trowel.
- Said gardening trowel was already a knife (or short sword) beforehand. It has a large magical stone either on the pommel or the hilt.
- Near the end of the book, the stone ends up saving the young man's life because he had been bitten/scratched/bled on by a creature (I remember "Wyrm" being mentioned) that's very essence was poison. The stone healed him of the affliction the wyrm caused.
- He kills the dreaded wyrm, collects the magical macguffin and then returns home to the farm where he reforges the knife back into a trowel.
I believe it might have been the first (or second) of a series, but my library didn't have any of the other parts of the series (this was back before I learned about inter-library loan).