create implication shackle -> cuffscreate implication handcuff -> cuffs
Shackles is aliased to shackle. Shackles implicates cuffs, but shackle itself doesn't.
Handcuffs also has pretty much the same oddity, but this time singular handcuff is aliased to plural handcuffs. Handcuffs implicate cuffs, handcuff doesn't.
Since singular cuff is aliased to plural cuffs, I don't see a reason these implications shouldn't exist.
Updated