What's wrong with duct tape?? Sorry.
I'd want something like a metal dowell into each part of the plastic. Will the saw come apart so that you can drill a pilot hole in each end of the broken pieces and use a dowell or one of the double ended lag bolts to screw the parts together? Use some epoxy(or JB Weld) between the 2 parts that would squeeze out as they come together so that any broken edges would be filled by the epoxy. Do both ends and reassemble. Might want to wrap the handle with some of the grip tape. I hate the feeling of having epoxy on my hands.
Otherwise I'd be a little leary of just gluing the handle back together. If the joint were to suddenly fail, you could have a loose circular saw to play dodge-ball with. Jim.
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