Late reply but those last two are Ko-Wakizashis, which are shorter katanas worn at the hip, behind the back, with the "Ko-" annotation meaning that they're shorter than an average wakizashi, being closer in size to a Tanto. Wakizashis were often worn with a katana to distinguish the wearer as a samurai.
When worn together, a katana and wakizashi are known as Daisho, literal translation is "Big-Little"
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