The Knife and the Sword: Fantasy

There was a place, beside the tang of the sword, for a knife to nestle in unobtrusively. The knife was gone from its place, and he felt the loss of it acutely every time he took up his sword. He'd given the knife to a lady, a long time ago, a lady who was going into a difficult place. He'd sworn that the knife, being part of the sword, would be able to protect her beyond what an ordinary knife might do. She'd smiled, a little sadly, and slipped the knife into her sleeve. Humoring him, he'd thought at the time, but she had kept the knife. Most women would have laughed outright at a sixteen-year-old boy proffering a knife in all earnestness to a woman of full years and power enough on her own. She had not, and maybe that--

Inspiration: A rather complicated Japanese word meaning something involving swords.
Story Potential: High.
Notes: And then he receives the knife back, as a message of ambiguous nature. And he goes. What was the difficult situation anyway? Intrigue and swords and court politics, oh my!