The horn's not re welded. The anvil was built w/ that small extension. I think it's either a farriers or carriage makers anvil. As to the large horn being broken off . . usually anvils which were captured during the revolutionary, & civil wars had the horns broken off so the enemy's farriers couldn't shape horse shoes. Or so the story goes.
For blade forging you'll use the flat more than anything else.
Nice find! Good luck!!!
Larry