I think it's primarily because it's not honorable, especially considering in what context it's mentioned in the PHB. YMMV.Patryn of Elvenshae said:However, many people who use poisons do so for Evil ends - which is likely why it is proscribed for Paladins.
I agree with Darkness. The description of the paladin code of conduct says that the paladin should "act with honor (not lying, not cheating, not using poison, and so forth)", so poison use is explicitly listed as a dishonorable act, not as an evil one. The DMG (pg.296) says that the "purchase and possession of poison is always illegal" but says nothing about it being evil. I don't think there are any other relevant descriptions of poison use in the RAW.Darkness said:I think it's primarily because it's not honorable, especially considering in what context it's mentioned in the PHB. YMMV.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.