What does 'wakizashi' mean?

Chapter 1: Chapter 1

"... but Andela was looking at her hard, trying to read something on her blank, blood-spattered face. Andela sighed. “That’s Muhjah’s wakizashi you have there,” she said. “Is that his name? I’m still piecing it all together.” “That’s his name, and he’ll want that back.” ..."

"...Her voice was a little too loud. The people closest to them moved discretely away. A new and alien rage was waking in Chiyo. She gripped Muhjah’s beautifully sculpted and utterly foreign wakizashi as if she might crush it to dust. Her knuckles were white, her body tensed, and her face took on a faint bluish tint. ..."

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Chapter 4: Chapter 4

"...It would have been better to remain in the meadow; the forest wasn’t particularly conducive to pitched sword fights. Both Muhjah and Senka carried wakizashi for such situations. Being shorter—twenty inches compared to the katana’s twenty-four to twenty-nine inches—they allowed for greater movement. But Chiyo had no such weapon. Hers was too long for the confined space. Yet again she felt herself a hindrance to them. Senka silently traded blades with her. He made ..."

"... balance. Chiyo gasped at the weight of the weapon she had been handed. It was significantly heavier than the pilfered katana she had been using and heavier than Muhjah’s own wakizashi that she used outside of Danbire. That Senka wielded it with such ease was surely miraculous. The three ..."