Joltenne is very VERY proud of her cooking prowess and her running speed. He can catch up to a moving vehicle somehow!!! O_O

Argentiums as a whole: Their silver hair with their respective hue, birthstone eye, and nail polish colors. The former is a symbol of their authority and an ode to their grandfather. The latter showcases their individuality and being destined for greatness.

Elio: Being generally calm, level-headed, observant, adaptable, and pragmatic even under highly stressful situations. Especially during battles and other competitions. Also being a genuinely good sport, despite suffering from a subcobscious perfectionalist mentality.

Kingston: Flexible wrists :o (helps to swish swish the sword real good)

Ruth: Her aim with throwing stuff is scary good and she's v proud of it.

For Jin she's proud of (most of) her scars. As both stories to tell, and reminders of how far she's come.
And for Mary it's probably her musical skills

Norra having her technical affinity thanks to watching her mom work on the Pokemon Transfer system, among other things.

Bozidar spending time with his Delibird and Pelipper Ice Fishing in the Czerajian Mountains, or providing some baked goods for Gael to sell at his cafe.

Paleni being able to use legit magic and be able to successfully use illusions for herself (and others if needed).

Odd's always been pretty dexterous with his hands (he can multitask like nobody's business, started at an early age helping his father with chores and carried over as a barista), and that's a skill he's always managed to pride in himself