The BladeForums.com 2024 Traditional Knife is ready to order! See this thread for details:
https://www.bladeforums.com/threads/bladeforums-2024-traditional-knife.2003187/
Price is $300 $250 ea (shipped within CONUS). If you live outside the US, I will contact you after your order for extra shipping charges.
Order here: https://www.bladeforums.com/help/2024-traditional/ - Order as many as you like, we have plenty.
That may not be the temper line but actually the line where the overcoated steel of the bit meets the softer steel of the body in older two-piece (three piece in double bits) axes. Then the steels rusted at different rates. It is not bad. Looks like a nice axe.