using shield will slow your weapon down some. WPF can increase swing speed up by about 15-20% if I remember correctly. also the speed is scaling, so slower weapons will see more benefit than already very fast weapons.
also, each particular swing/animation for each weapon type has reach and speed bonuses associated with it. I am only familiar with 1h speeds, but I would assume any extra reach also comes at the price of speed.
left to right: shortest and fastest
Overhead: middle
left to right: slow but extra reach
thrust: lots of extra reach but very slow
SWING REACH MODIFIERS
1h
Overhead = +0
Left-to-right = +0
Right-to-left = +19
Thrust = +61
2h
Overhead = +15
Left-to-right = +17
Right-to-left = +13
Thrust = +80 *not accurate anymore with the new animation*
2h Polearms
Overhead = -15
Left-to-right = -7
Right-to-left = -2
Thrust = +19
1h Polearms
Thrust = +50