I assume it recreates the disruption property of the same name in the DMG magic weapons section. Probably for 1 round/level. Bladebane in Unapproachable East recreates the Bane property for 1 round/level in the same way, so I'm betting what 3.5 is using for it is basically the same spell as in UE, but using a different magic weapon property--in this case, disruption.
Theoreticaly, disrupting weapon should be the prequisite spell to create a magic weapon of disruption, rather than anything else. Not sure 3.5 did this, however.