I do believe that Ieyasu’s fighting style is the most masochistic way to fight.
He takes up a burden with his hands. He hurts himself with every punch. Unlike swords that break and must be reforged, unlike spears whose poles can shatter and must be remade, the hands are a part of the body. Knuckles and wrists can break, but the pain is something that he will always have to live with. Ieyasu can’t mount his own arms on a wall after he’s done fighting with them. He will have to live with the blood and the scars forever. With every single day, he will know that he had to fight his way to get to where he is. With every blow, he has to feel flesh bruising and bones breaking beneath his fists.
Ieyasu has to have resolve with every blow because he has to throw it personally. Fists make it personal. To bludgeon someone to death every time you’re in battle gives a testament to how personal he takes his burden. He used to fight with a spear and could easily go back to it, but he saw how hands can do evil when it came to the Toyotomi. He wants hands to do good and he takes it upon himself to carve his way through blood and bone, even if it means breaking his own hands to do so.