No your wrong, the haste cap isnt in the percentage its in the delay. The weapns delay can go no lower then 10. With the exception of the Vah Shir song in which case, and only that case, can it go below 10.
There is no minimum delay for weapons. Parse a Ranger with a Revultant Whip (14 dly) at max hast cap (100%) and you'll see him attacking more than once per second. It only appears that the min delay is 1 second because the EQ logger only logs things once every second.
Max hast cap is 100% with item/spell Currently, 2 Bard songs and monk epic (which is a self-buff bard song) can lift you over this cap.