In the default 1.68 script for Terrifying Rage it does a Fear saving throw. If it's failed and the creature's hit dice are below those of the Barbarian, then a paralyze effect is applied. The comment in the script implies that it used to be a fear effect, but is now paralyze. If the creature has hit dice equal to the barbarian, up to twice (but not including twice) what the barbarian has, then instead of paralyze it lowers all saving throws by 2 and decreases the creatures attack rolls by 2.
So, increasing the barbarian's intimidate skill raises the DC to save. To make it easier to save against the rage, increase your will save or get immunity to fear. It's not a fear effect, but a fear save or immunity will stop it. At least that's what I make of it.
Of course, this is all the default Bioware stuff. I've no idea if Layo modified it.
