Why is 4 frame zeal important?

[Wyrm]

Really, if you're not a speed freak, it's not that important. Having a faster attack allows you to get in and out of a situation faster. If you've got additive effects like Crushing Blow or spell castings on attack, it'll let you release more of them in a shorter amount of time. For builds that rely on damage coming from sources other than their weapon (say, Holy Shock/Freeze) you'll be able to apply more damage per second than with a slower weapon.