My Shovel Knight amiibo is nicknamed after David Spade, since a spade is a type of shovel. The most logical thing to would be do the same for the other three: name them after famous people who's names can be interpreted as puns relating to each knight...
09/12/2017 10:46 AM
Plague Knight → "Pete D.", as in the Pixar Studio director Pete Docter.
Spectre Knight → "Lee Ving", musician/actor who was Mr. Body in Clue.
King Knight → "StephenK" as in the horror novelist Stephen King.