Thanks @floppyamon for this post on Abraxas (link). Kaneki’s arm looks like a shield, which reminded me of an illustration in Zakki.
tg:re 74 pg 16 (mangastream)
Zakki (pg 81)
Annotation for the above from Ishida.
I think he’s saying this was drawn when TG ch 50 was [released/drawn?]
This could work! I guess Ishida would be squishing the two arm functions into one arm (since the right arm had the whip and the left the shield), but I was wondering what the purpose of his shovel arm was