Comment by DavidAdams

A "bodkin," an archaic word for a small knife or sharp implement, is probably a diminutive of "bod" or dagger. A "jerkin" or a tight vest, might be a diminutive of the Dutch "jerk," (dress), but all of these words are so old it's hard to nail down their etymology. As other commenters pointed out, today's diminutive suffix is -y/-ey, used mostly for childhood nicknames and baby-talk names like horsey.