Yes, Sarin which is weaponized is a WMD. "Old WMD's" are any that were made prior to 1946, but they are still classified as WMD's. The CWC and GC make no provisions for pinhead analysis of munitions to determine their lethalness or lack thereof, they make no stipulation that the criteria revolves around Democratic hacks trying to get elected, or fucktard idiots on a message board who can't spell or apparently read and comprehend plain English. The CWC and GC don't define WMD's merely based on your opinion of what might cause mass destruction, or mine. They don't delineate between WMD's that are known about, and ones that aren't known about, they don't distinguish between WMD's that are rusty and ones that aren't, and they don't set any criteria for an arbitrary point in time where the WMD will no longer be a WMD. They state, quite clearly, that weaponized Sarin is a 'Schedule 1' Chemical Weapon, (aka: WMD), and prohibit the possession, production or stockpiling of these WMD's, as well as the precursor agents involved in making them, and Iraq is a signatory to the CWC and GC.
Now.... Do you have ANY evidence to suggest, that ANY international body, at ANY time, has stated ANYTHING to the contrary, or interpreted WMD's to mean ANYTHING other than what is stipulated by the CWC and GC? If so, you need to present it now, and stop pretending that you know more than everyone else on this subject.