The largest blanchard head knife i have came across.

This is insane! Are you planning on actually using it? Might be a cool piece to put on a wall in your workshop.

For a second I thought I was looking at a picture of the moon against the night sky until I scrolled down lol.

I would probably use that specifically for skiving the ends of watch strap linings or delicate leather wrapped trinket boxes ;D

I imagine that would be used in a rolling motion for straight cuts through thick hides. Likely for tannery use cutting whole hides into sections, but that's a wild guess.

this is for whale skin i assume

I heard size doesn’t matter, but damn that’s a big knife