We need to be able to save more stuff in our armoir

[Beckett]

Try checking the Calamity Salvager. As a quest reward, it's quite likely you can repurchase the Scion Adventurer's gear there.

Edit: Yeah, just checked. It's on there. Feel free to toss your Scion's set if you need space, you can always rebuy it for like, 500 gil total.