I don't remember all of the context there. It's a hazard in being so quoteable.

Essentially:

Calming the Tempest will significantly increase your chances of making most saving throws (might only be vs. spell, I forget). Obviously this is a big help if you're only slightly or moderately geared for save, but further: if you're geared for a lot of save, your chances of making a save improve substantially beyond what any other character can achieve. It's an excellent legacy for fighting anyone who offensively casts/communes/calls/etc.