harden vs face-harden

harden and face-harden both are verbs.

Word	Noun	Adjective	Verb	Adverb
harden	No	No	Yes	No
face-harden	No	No	Yes	No

As verbs, face-harden is a hyponym of harden; that is, face-harden is a word with a more specific, narrower meaning than harden:

Other hyponyms of harden include callus, anneal, normalize, temper.

harden (verb)	face-harden (verb)
become hard or harder	harden steel by adding carbon
make hard or harder
make healthy
cause to accept or become hardened to; habituate
harden by reheating and cooling in oil