Apparently it's a mortise chisel.
https://galootopia.com/old_tools/chisels/swedish-chisels/berg-chisels/berg-trident-mortise-chisels/
Good find! Thanks
@chiroshi started
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Apparently it's a mortise chisel.
https://galootopia.com/old_tools/chisels/swedish-chisels/berg-chisels/berg-trident-mortise-chisels/