I know I’m late to the replies here, but basically if your happy with the shape of the handle before torching it, leave it be and grab the torch.
After torching, depending on how heavily you burnt the wood, buff with sand paper. I like to reveal some of the lighter wood beneath the burnt surface, like blonde highlights. To so this start with 220 or 300 grit, then work your way up to final desired grit.
when I start with the low grits I don’t really sand until smooth. I like to leave some texture in the “scratch pattern”. That said I will go up to 1500 in sand paper, then buff with micro mesh. This gives the handle a nice sheen an visual depth while still maintaining texture from scratch pattern. Then I’ll finish with oil.
here’s a couple pics, 2 Mazaki gyutos I reshaped prior to torching, a dalman I just “highlighted”, and a saya as well
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