Purchased a Dremel to replace the 2 rigid tools that I had,no comparison,the Dremel has stood up where as the rigid tools are noisier,vibrate and get very hot and both broke with out a lot of use.
I have never cut deer antler, but since these oscillating tools can cut wood and metal, it shouldn't be a problem. I think the challenge would be cutting so the two sides are parallel (if that is needed). If the diameter of the antler is small, you could also look into a high speed rotary too (like a dremel) with a cutting disc. Good luck!