831.2. If a Unit has Disarm, or has been granted Disarm, and is granted Disarm by an additional source, the Disarm Value of all granted Disarm keywords is summed. Example: Clanging Sentry reads "Your Mechs have [Disarm]." If you play a second Clanging Sentry, both of them will have Disarm 2.
831.3. Disarm, and whether or not a unit has Disarm, is a characteristic of the Unit and may be checked or referenced by other Game Effects.