Frail, liable to sin.

Not as it should be; not in accordance with what is considered morally correct, appropriate, etc… Applied to a particular person or thing. Now rare.

Capable of falling (in various senses); liable to fall.

Prone to lapse into sin or folly, spec. (in Christian contexts) liable to fall from a state of innocence. Also (of a person's mind or memory): prone…

Capable of sinning; liable to sin. In later use also (frequently in humorous contrast to impeccable): fallible, imperfect, flawed.

Liable to pass or change; liable to err or fall. Const. into. ? Obsolete.