User blog comment:Hitsuji Mamoru/FGO-style Servant Creation Room/@comment-27971189-20170203180430/@comment-4802891-20170204121140

In my opinion, Kojirou is summoned as Assassin because that's what he was in FSN. That's just paying homage to a legacy at this point.

He should have been a Saber, and maybe one day we will get just that... My safest bet is that he will appear in chapter III of part 1.5 and be labelled Saber (with levels and stats of a 1-star grailed to level 90). Well, "guess". I'm not betting anything on this.