I'm not entirely sure if this, because it's technically not an attack, so I don't believe it would be affected if the weapon was upgraded.
The 2-hand R2 on the Chaneller's Trident does the dance, and buffs the user and nearby friendlies for a short period of time. This wiki page describes the effects of the buff in more detail.
So I was wondering, because like most other weapons with special attacks, would the buff dance be increased in some way if the Trident was upgraded? In either duration, or effect, or both?
Best Answer
I've just done some testing and the result is: No, upgrading the Channeler's Trident does not have any effect on the buff, increasing neither its strength nor its duration. While I was already on it, I also tried to find out the exact effect of the buff on different damage types and weapons.
The conditions
I've done this test on the currently most recent version 1.06 with calibration 1.08 on Playstation 3. The character I was using is on new game +, though that should not make a difference. I was testing the damage values on Stray Dogs outside of McDuffs workshop in the Lost Bastille.
These were the weapons I used:
The results
The buff lasts for exactly 20 seconds in all upgrade stages. Upgrading the Channeler's Trident also does not change the effect of the buff in any way.
I have tested the melee weapons with and without counter attacks, meaning an attack during an enemy's attack, that does more damage. The regular attack is the value on the left, the counter attack is the value on the right (e.g. 100/200).
Flame Swathe did 1012 damage unbuffed and 1063 damage buffed, meaning a 5% increase.
Lightning Spear did 476 damage unbuffed and 500 damage buffed, meaning a 5% increase.
The Hand Axe used one handed did 102/113 damage unbuffed and 110/121 damage buffed, meaning a 7.8%/7% increase. Using it two handed did 123/135 damage unbuffed and 133/146 damage buffed, meaning an 8.1% increase.
The Estoc used one handed did 106/128 damage unbuffed and 114/137 damage buffed, meaning a 7.5%/7% increase. Using it two handed it did 128/153 damage unbuffed and 137/165 damage buffed, meaning a 7%/7.8% increase.
The Key to the Embedded used one handed did 260/390 damage unbuffed and 276/414 damage buffed, meaning a 6.2% increase. Using it two handed did 312/468 unbuffed and 331/497 buffed, meaning a 6.1%/6.2% increase.
Conclusion
Upgrading the Channeler's Trident has no effect other than increasing its melee damage. The duration of the buff is always 20 seconds. The buff increases the damage of miracles and pyromancies by 5%.
However, I did not quite understand how the buff for physical damage is calculated, as it differs with changing weapons and attacks. The damage increase for these physical attacks is roughly between 6% and 8%.