With todays patch this calc and all others need major revision
All weapon styles should have the same number of main hand attacks per minute if you stand there holding down the attack button. (Except monk unarmed combat, which is around 10-12% faster. Flurry of blows!)
See first paragraph of my post before reading this next section, as these are close to the top of "things most likely to be adjusted in the future":
Dual Wielding:
Off hand attacks on attacks #2 and #4.
ITWF adds off hand attack on attack #3.
GTWF adds off hand attacks on attacks #1 and #4.
Ranger Tempest III adds main hand attack on attack #3.
Monk:
TWF adds additional attack hooks on attacks #2 and #4.
ITWF adds additional attack hook on attack #3.
GTWF adds additional attack hooks on attacks #1 and #4.
Two Handed:
Glancing blows on attacks #1 and #4.
GTHF adds additional Glancing Blows on attack #3.
We set the time to complete a two swing mobile attack chain to equal a little over one half of the time to complete a four swing standing attack chain.
These changes are not a fully comprehensive solution to some combat animation problems we have, but we think they'll go a bit to address some of them.
You may see them again in the future. We'll probably assign the old fifth attack animations to some special clicky-attacks. (Sped up as necessary to keep them optimal.)