In my line of work, bigger keys are drilled and tapped (prior to installation) and are removed using a bolt as a jack screw. Smaller ones are removed with a pair of side cutters.
I had to Google what a feather key was...never heard them called that in 35 years of machine repair.
FYI for the rest of the inquiring minds, a feather key is a square key with rounded ends that fits in a keyway machined into a shaft with an end mill ( a pocket ).