Do some tests yourself mate.
Get on your STF, go full agi retard.
Grab a slow weapon, such as the 1h bar mace.
Hop on EU3, take a few swings, check how fast your swings are.
Get rid of your WPF and have a couple swings again. Compare the speed of the swings.
If 1st is faster, the number shown ingame is irrelevant. If they are approx the same speed, then try to stay below a certain threshold.