Was looking at it in the CK, it is a shout that adds an enchantment.

At first, checked the Shout's magic effect, but it does nothing other than giving the enchantment so I thought "maybe the enchantment controls the attack speed bonus", but then I went to the enchantment's magic effect and nothing... Then I checked both MGEF for scripts but still nothing.

After looking at the Elemental Fury shout, the magnitude is specified in the SHOUT form but I still don't understand how it is applied.