This blade has been mentioned. The knife is called a Loomfixer. Maybe someone can explain how that widened blade is used. I don't know exactly - it is easy to guess it is used to fix the warp or weft on a loom. Does anyone know for sure? It is not a sheepfoot.
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Since a Sheepfoot's primary use was to trim hooves to keep sheep from getting crippled, a widened blade would be a detriment, making it harder to turn around a hoof as you trim it.
In fact I suspect a Lambsfoot blade makes a better "sheepfoot"!!

Go figure!!!