This is NOT the voice of experience, but only that of an old materials editor...
Good malleable iron will take a lot of bending, or hammer-whacking, cold. If you heat malleable iron to red heat the graphite will re-form as flakes, which essentially turns it back into cast iron (which is what malleable iron is until it is given an extended soak at high temperatures). That's not good, of course, if you intend to bend it.
Caveats: 1) I've never tried it. 2) I don't know how long it takes at high heat for malleable to revert to cast iron (it usually starts as white iron, for the picky ones -- it shouldn't matter upon re-heat). 3) I have a second concern, which is that iron with that much carbon in it has a pretty severe hot-short behavior, so heating it with a torch could make it break off easily.
I'd bend it cold. But then, it's not my handle. Good luck.
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