unshakable vs unassailable

unshakable and unassailable both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unshakable	No	Yes	No	No
unassailable	No	Yes	No	No

As adjectives, unshakable and unassailable are synonyms defined as:

Other synonyms of unshakable include bulletproof, ironclad, watertight.

unshakable (adjective)	unassailable (adjective)
without flaws or loopholes	without flaws or loopholes
marked by firm determination or resolution; not shakable	impossible to assail
	immune to attack; incapable of being tampered with