What is your rarest SE razor? I have two candidates, both of which take proprietary blades but which can be shaved with as I have done so. They are a Eagle Deluxe lather catcher and a Gem Zinn lather catcher. The Eagle takes a Gem style blade but a version which is shortened vertically by about 0.160" or 4mm from Gem blade stock. I have made up blades for it from modern Gem SS PTFE blades. The Gem Zinn, only made for a very short time circa 1905-06, takes a proprietary thin disposable blade but can be used with a modern Schick injector blade or despined and shortened vertically Gem blade. The razor itself is a lather catcher design with a blade holder that opens like a binder clip to grip the blade. The Eagle is a mild shave while the Zinn is much more aggressive. The top two photos are the Gem Zinn while the lower two are the Eagle.
I base scarcity estimations on how often I have seen these offered on ebay, only once each.
I base scarcity estimations on how often I have seen these offered on ebay, only once each.