As long as the IAS isn't on your off-hand claw, it's counted(regardless of whether it's on weapon or armor, all equipment IAS is treated the same for Assassins).
i know how ww ias counts. just substract the weapon ias from the WSM and the bps are -10 and -35. So a 0 speed claw reaches the last bp. a tuc need an ias jewel with some nice mods on it though