Armed Interdiction was a technique in an August 2007 post by Kromm http://forums.sjgames.com/showpost.php?p=447559&postcount=15
November 2013's Pyramid 3/61 "Way of the Warrior" page 6 (in More Power to Dungeon Warriors) this was adapted as the briefer Interdiction.
The default changed from -2 to -3 via addition of the "Parrying a running person doesn’t count as parrying a heavy weapon" drawback in Pyramid which was absent in the 2007 forum post, which explicitly said:
- If you do strike your opponent for damage, then this counts as a parry against a heavy weapon; see Parrying Heavy Weapons (p. B376). The charging fighter's "effective weight" equals his ST. It's very possible to snap off a weapon attempting this stunt!