The piece of clothing the soldier has, whos is it? Is it arthur's?

i guess you meant that time where he met sylvia. i checked that chapter where they met but it doesn't resemble to what arthur was wearing back then. he wore plain clothes like literally plain

Maybe it is the clothing of the elf he doesn't like Idk

I’m pretty sure it’s supposed to be like ppl from the other continent or whatever or whoever the OTHER is, I do think though that the other has a relation with Sylvie and/or Arthur’s past