Exactly, degraded. Which means they were not usable as weapons grade at the time they were found post-invasion. Sarin degrades fairly quickly so it has a limited shelf life (after several weeks or a few months), and by the time we found any shells containing that chemical from pre-gulf war they would have been useless. Mustard gas, even prior to degradation, is not significantly lethal, but mainly causes painful burns. And considering that these were found in artillery shells, even if they were not degraded, they are useless to anyone wanting to use them as a terrorist weapon.
The point is there was no active program in place in Iraq for the production or potential use of WMDs at the time we invaded them for that reason. So at the time, they were not a "smoking gun" to anyone even in the region, much less to our country.
Our government was told a lie, they believed it without investigating whether it was true, and they invaded a country based on it.