The easiest, would be to grind it round, similar to the heel. Draw the profile with a colored sharpie for contrast and a coin, washer or copy of the heel profile. Then, file with a Diamond plate/ diamond file or low speed with a Dremel and a medium sanding drum, quench frequently in a glass of water.

Go slow, clamping the blade, edge up, in a vice padded with wooden jaws and or leather. Overheating will ruin the temper of the blade and it will never hold an edge.