Currently, doing this seems to last about 2 or 3 rounds. While poisons to do this with are available in decent amounts, I think it would be nice if this could have it's duration increase to be similar to an alchemists fire on a weapon.
Make it so it does not stack with darkfire or flame weapon and it could be a nice alternative all the while giving a small bonus to archers that like to cry a lot. Poisoning arrows is possible ! :)
Maybe even a /c poison weapon/arrow command so it does not break stealth!
I approve of a /c command to apply poison to weapons, but the DM's may not like it because it allows you to apply poison to a weapon without using an action to do so. Which could lead to poison becoming a little too easy to use frequently.
And I'm not sure if arrows can already be poisoned, but if they can't, it would be a nice change for arrows/bolts/darts/shurikens to be poisonable.
I don't agree that the duration should be increased. The abilitydrain on hit that these poisons give is just too strong to be walking around with for an extended period of time.
Ranged weapons are poisonable, you use the poison on the throwing weapon, or the ammo item in your equip slot. Poisons are very strong, and should not last longer. More quests with poison drops though, IMO. There's one guaranteed source that's 3-6 and then it's rare.
I think people tend to vastly underestimate how useful poisons can be and are. AI doesn't use restoration potions or antidotes or antitoxins. Con damage against large HD creatures can drop their HP more effectively than spells, dex damage makes high AC creatures easy to hit, and str damage can seriously reduce AB and damage from the opposition (though it typically won't encumber monsters since the engine is weird like about encumberence on NPCs). And of course this is all good against PCs too. Making it last as long as flame weapon or darkfire would just be waaay too long.
I wouldn't mind a small increase in time.
Having used poison on arrows before, I can attest that it is very useful at weakening enemies, and the duration is fine as it is IMO.
Though I wouldn't mind a little note on what kind of damage a poison does, like 'this poison is known to sap muscles' or 'weaken their immune system' or similar.
Hmm, 3 rounds of poison? I'd say 30 seconds would be fine, 5 rounds IMO.