Plastic glue won't work on resin.
I cannot see easily because the model has been sprayed black, but I think a good way to handle this would be to test-fit it to see how tight the fit is. If it is a clean break and mates cleanly, a drop of superglue will hold it well. If not, use a small ball of green stuff sandwiched between superglue to make a custom fit.
Let that dry for a good 24 hours.
Then, take some very small bits of green stuff and make rose-vines wrapping around the scythe and crossing the break. Drops of superglue will hold them in place well. Then make a rose or two to go on the vines, so it looks like part of it.