I don't have a source for the number of people in encounters but I think it was at a Fanfest/TGS or something with Koji and YoshiP. That's the explanation that makes sense to me in any case.


As for there being only 1 WoL, we know there CAN BE as Ardbert, Lamitt, Nyalbert et al. were all expressly warriors of light, same us we. On the source we DO have someone (implied in English, stated point blank in JP) who we adventure with and is a warrior of light: Ysayle.

Yshtola sees her sacrifice in Azys Lla and says (approximate because I don't have the scripts handy):
EN: This aether... It was a crystal of light! She was one of Her chosen!
JP: Could it be.... She too was a warrior of light