Well,I do not see a problem with beaking the corner,especially in stainless
I suppose some folks might do a fine job with a dremel,but I think you would be more likely to mess up with a dremel.
I might use a very fine oval needle file to put a uniform .010 or so 45deg chamfer down the line.Then,to see better,you might marker it then just break the new corners,so you have somewhat made 3 flats of an octagon,on a small scale.
Then I might use about a 320 or 400 grit polishing stone,or even an india stone,to blend it to round.Use a bit of oil and a light touch,maybe follow with a little 500 then 600 wet or dry and some oil.Then,maybe a little maroon scotch brite for a brushed look.
under a finer image quality,the part looks like it has a glass bead finish.thats pratty easy.Its not the same as blasting with sand,it just frosts it.