Mages operate on the 200 formula. (Magery + Poison skill) / 2 = level of poison.
Less than 65.1 : Level 1 poison
65.1 to 85 : Level 2 poison
85.1 to 99.9 : Level 3 poison
100 and higher : Level 4 poisoning
Warriors operate on a separate formula. It's based on their poisoning skill only. That formula is:
The Poisoning skill will give a (Poisoning Skill)% chance to increase the level of poison delivered by 1. The blade must have poison applied to it. The power of the poison depends on the type of poison used and your poisoning skill.
With Poisoning skill 0.0 - 19.9 you can inflict Level 1 (with a chance of level 0)
With Poisoning skill 20.0 - 39.9 you can inflict level 2 (with a chance of level 3)
With Poisoning skill 40.0 - 59.9 you can inflict level 3 (with a chance of level 4)
With Poisoning skill 60.0 - 100.0 you can inflict level 4 (with a chance of level 5)
For example - Deadly applied to a blade. Poison skill at 80. You inflict level 4 poison (deadly) with an 80% chance it will bump to lethal (level 5).
Most warriors take the poison skill to around 80. No accidental finger slips and never fail to poison a blade. Plus it saves you 20 skill points.
Mages on the other hand will take the poison skill to match their magery. 115 Magery, will have 85 poison. This will make poison fields and the poison spell level 4 (deadly).
More information can be found here:
http://vboards.stratics.com/showthread.php?p=795037#post795037
