Tripping and cover (and a blade barrier question)

[ZatriX]

Either I don't know how to search or...

Anyways, the question is simple: A player is trying to trip an NPC through cover (Blade barrier spell in this example). Is it allowed at all? I mean cover denies AoO, so it puts the poor NPC at a disadvantage?

Second part of the question is the spell itself. By RAW it states


Any creature passing through the wall takes 1d6 points of damage per caster level

Will attacking with melee weapon through it also deal damage? Maybe at least to your weapon?

[Barsoom]

Yes, seems like the NPCs is at some disadvantage. He does get the +4 to AC though.

As for damaging a weapon, RAW is very specific: the Blade Barries does damage to any creature passing through it. You can houserule damage to a weapon, but I advise against it. Because then, by logic, the Blade Barrier will also have to deal damage the armor of all creatures passing through it, and their gear. Bookkeeping nightmare.