Headcanon: Edge of Seventeen
When Lestara came and adopted Sona, they lingered just a little before leaving so that Sona could, in a way, say her last goodbyes. Because the journey from Ionia to Demacia and back again is a long one no matter how you go about it, and even if she did return someday it would likely be a long time later.
Which was fine since Sona didn’t have much tying her down to Kashuld in the first place. So they got to see the sights of the city in a way Sona had never seen before, and with her mother being so wealthy she was allowed to buy almost anything she wanted. Though Sona being a simple, humble girl at the time only wanted a few things; a peach wood comb with beautiful carvings, a silk robe (that no longer fits her), an assortment of sweets and fruits that she’s long since eaten, nice slippers (that she wore out), and - most confusingly to her mother - a kaiken (a small knife).
Ever since she could read, Sona was enamored with stories of swordsmen and warriors and foreign “knights”. Of course being stories her ideas were left very idealistic and embellished, but all the same she found the idea of being a swordsman’s wife very romantic. The culture she grew up in supported this idea, since the majority of the working class were either farmers or merchants where she grew up. So marrying a bladesman was akin to being married to, say, a pro sports athlete - with all the prestige that brings, and the benefits of living a (fairly) comfortable life.
Besides the more romanticized ideas she had about it, it also likely would have allowed her to pursue a higher education - something she could only dream about when she was younger. She’d have been expected to have a basic level of combat training in case she needed to defend her family as well. Thus, the kaiken.
But Sona never learned how to use it. She left Ionia was she was nearly 18 years old, and even if she hadn’t she was about to be sold to a merchant as his wife, so any idealistic dreams she had were never going to come true anyway. Buying that small knife was a kind of wish fulfillment instead. It made her happy just to hold it and pretend. Of course, at the time she was so happy to have been adopted in general that it was hard to be sad about unfulfilled dreams. She was too busy being reborn in an entirely new life.
She still has the knife, but it’s tucked away somewhere in her room as just another nostalgic keepsake.