Yes, definitely a massager, but probably given the size and weight for the back and perhaps thighs and calves.
Those edges look to sharp for a massage thing. Whatever it is, it is beautiful. Gold sure stands the test of time. And amazing the symmetry and the sharpness of the edges and perfect lengths of the grooves. I guess it must have been machined on some type of ancient lathe?? It wasn’t just some guy whittling away at it while waiting for dinner.