Start by breaking the crab legs apart, using scissors or crackers.
Discard the shells.
Combine the garlic powder, onion powder, all-purpose flour, half of the Old Bay seasoning, and half of the cayenne pepper in a mixing bowl. Add salt and pepper to taste.
Whisk well, until combined.
In another bowl, beat together the eggs and the water.
Dip the crab legs into the flour mix, on both sides. Shake off the excess.
Then dip them into the egg mixture.
Combine the other half of Old Bay with panko and the cayenne pepper in another bowl.
Dip the legs into the breadcrumb mixture. Press the legs a bit so that the breading sticks.
Heat vegetable oil, preferably one with a high smoke point, in a skillet and fry for a few minutes.