This rare effect rune tends to increase the Magic Repel rate of the wielder, offering him to smash any offensive magic back to the caster. If any amount of Magic Repel is already available, the value of this rune will be added to the existing percentage.
You can happed to miss the Barrier Rune completely, while playing either Suikoden II or III due to its rare appearance. Magic Repel is nice to have, yet undependable in its behavior. If you get one from the enemies on Banner Pass or the corpse on the Flame Champion's Hideaway, try it at least in some magic feisty boss battles. This rune is quite a nameless one and was never used in any later game whatsoever. - Celes