promise vs swear off

promise is a noun but swear off is not a noun.

Word	Noun	Adjective	Verb	Adverb
promise	Yes	No	Yes	No
swear off	No	No	Yes	No

As verbs, swear off is a hyponym of promise; that is, swear off is a word with a more specific, narrower meaning than promise:

Other hyponyms of promise include pledge, plight, contract, undertake, guarantee, undertake.

promise (noun)	swear off (noun)
grounds for feeling hopeful about the future
a verbal commitment by one person to another agreeing to do (or not to do) something in the future

promise (verb)	swear off (verb)
make a promise or commitment	promise to abstain from
promise to undertake or give
make a prediction about; tell in advance
give grounds for expectations