The sleeveless cuff is a dead giveaway for Drake if you're familiar with her second ascension. It's actually a lot more recognizable compared to the gauntlets. Gilgamesh is probably the hardest to identify if you miss the blue strap actually.
Also, the theme is the singularity main helpers plus Mashu and Da Vinci so it's pretty easy to tell who's supposed to be there once you realize that.
Mordred
Fourth SingularityNero Claudius Caesar Augustus Germanicus
Second SingularityFujimaru Ritsuka
Fellow masterLeonardo da Vinci
Universal Genius; Chaldea StaffJeanne d'Arc
First SingularityBedivere
Sixth Singularity