Fionn/Enalius you say?? 🙊
In Silene's Lore Lesson, we see Fionn and two more figures making the Starsword, which Bryce can't make out in the snow — presumably Enalius and Oleanna, who ACOTAR legend tells us as being there too. Theia? Probably there to but there's no reason to hide Theia, so I don't think it's her.
Twin blades, wielded originally by Enalius and Fionn. The King and General. And then Enalius SACRIFICES HIMSELF, Fionn takes the dagger, and NEVER USES IT. It's not just "Oh I'm taking it for myself"! It's "This belonged to my dear friend, I'm keeping it, and no one else is using it, NOT EVEN ME".
So yes, I'm choosing to read it as not entirely platonic and a bit gay lmao