off your guard vs off his guard

off your guard and off his guard both are adjectives.

Word	Noun	Adjective	Verb	Adverb
off your guard	No	Yes	No	No
off his guard	No	Yes	No	No

As adjectives, off your guard and off his guard are synonyms defined as:

Other synonyms of off your guard include napping, off-guard, off guard, off her guard, off one's guard.

off your guard (adjective)	off his guard (adjective)
not prepared or vigilant	not prepared or vigilant