Unknown maker, surely Sheffield, ‘Superior Temper’, and it is, super hard, fine grained steel. It took me several hours on a slurried Shapton Glass HR 500 just to set the bevel. It’s a bit of an odd duck, the heel says ~1800-1830, the upswept nose and vestigial dip at toe says late 1700s. It’s big, 7/8. Soap was 3P lathered with a Keyhole 2, and Myrsol AB finished up.