According to
lucy.allakhazam.com spell data, the original land and fade messages were, "You feel [something]." and "The [something] fades." So probably something like, "You feel shielded from harm." and "The shielding fades." Apparently the "You no longer feel pain." message wasn't added until a newer version of the spell was introduced in 2008:
2008-07-09 02:52
Changed 'Wears off' message from "The placeholder fades." to "Your invulnerability fades."
2008-07-09 02:52
Removed 'Cast on other' message: is covered by a placeholder message.
2008-07-09 02:52
Changed 'Cast on you' message from "You feel a placeholder message." to "You no longer feel pain."