I do agree that the wooden parts were flame treated. Seems to be done by the engraver, to bring out his/her engraved pattern.
And I think the blade was custom made because this kind of peening/marking takke too much time to be a production blade. For me, the sword 's decoration suggested its personal/home defend purpose. The "ติ" inscription could be someone 's name, likely to be owner (please enable Thai encoding on your page).