Whenever it is swung, the "sword of the abyss" cuts open a 1 ft diameter portal to outer space. The portal will close by itself after two seconds. The portal shrieks as air rushes into it. As a result of the air motion, to some extent anything nearby is pulled towards the portal.
Further details: The portal opens at the fastest point of the sword's swing, which we may suppose occurs when the wielder's arm is fully extended, just before the sword strikes the enemy. The portal is a two-sided circular disk, i.e. stuff may enter it from either direction (effectively two portals back to back). The portal opens so it just touches the point of the sword, and a flat side of the portal is perpendicular to the sword at the moment of creation.
I know that the speed of air at the portal will stabilize at the speed of sound. But perhaps there is a ramp-up period where it isn't going that fast for a second or two (I don't know, do you?).
Possible effects I can think of:
- Everyone within X ft (6 ft? 10 ft? how far?) of the portal is yanked off their feet by the sudden wind
- The sword of the abyss, being the object closest to the portal when it is created, is yanked from its wielder's hand into the portal
- Or maybe neither of those things happens, and the wind is manageable
What are the melee combat effects of the air flowing into such a portal? (1 ft diameter portal, open for two seconds)