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If you want to be period-accurate, and not use wood, I'd say bone (bovine) is the right choice.

Indeed: his book is based on his personal collection - which is entirely on another (museum+) level!

It's out of print, but he himself is selling it on eBay from time to time. His nickname there is "safetiesfirst".
Where did you stumbled upon this razor BTW - just curious:)

Based on Renzo Jardella's book (see p.8 for reference), I'd say this razor is of MUCH earlier period - 11-12th century.
This is a terrific find - congrats!