It would seem that some buffers disappear before their duration is done while other buffers can stack. If you do something to your weapon, such as use a sharpening stone on it or put some poision on it and then enter an instance, that buffer will disappear.
Minimum requirements:
A level 20 paladin
At least 10 talents in the holy talent tree, and 1/2 talents in the Improved Lay on Hands.
Rank one of lay on hands or a higher rank. This spell can be learned at level 12+
Recommended requirements:
A level 21 paladin
At least 10 talents in the holy talent tree, and 2/2 talents in the Improved Lay on Hands.
Rank one of lay on hands or a higher rank. This spell can be learned at level 12+
To achieve the maximum benefit from this, you must be able to log on, use lay on hands on yourself, and then log off as quickly as possible. People can not see this buffer stacking on you nor can you see it stacking on you. You can, however, see the difference if you open up your character status and check how much armor you have. When I am using devotion aura and my shield, I normally have a 49.5% damage reduction from all melee attacks. It took me a while, but I was able to have a 63.9% damage reduction from all melee attacks. I think this worked because when I used lay on hands on myself, and then logged back on 45 minutes later I still had the buffer. The part that sucks about this exploit is the buffer lasts for less than two minutes, and there is a 40 minute cooldown on lay on hands if you have 2/2 in the improved lay on hands talent.