Why not make a background story on how you came into using your fist from your sword like "One day you broke your sword in the middle of a heated battle then as a last resort you thrusted your bare hands right at the monster, killing it in a single blow. Realizing your true potential lies in your fists, not your arms you decided to develop your martial arts skill as a pugilist, etcetc." Creativity helps a lot for RP development.