Went ahead and tested how zanshin effects counter rate with seigan up.
Had about ~20 or so mandies in abyssea attowha to counter against using a low damage great katana.
Code:
Melee Damage Taken
Player Melee Dmg Melee % Hit/Miss M.Low/Hi M.Avg #Crit C.Low/Hi C.Avg Crit%
Nerji 3289 96.85 % 4171/5014 0/26 0.20 261 0/44 9.56 6.26 %
Passive Defenses
Player Evasion Evasion % Parry Parry % Counter Counter % Intimidate Intimidate %
Nerji 4486 42.21 % 1409 22.99 % 539 11.44 % 0 0.00 %
If this calculation is correct =1.96*SQRT(0.1144*(1-0.1144)/(4171+539)) It gives a confidence interval of +/- 0.909%
This type of counter also has an accuracy check (tested using a staff) so this falls within the expected value of 12.5*0.95 (zanshin/4)*accuracy cap
I also tested the counter rate of Unkai Kabuto +2
Code:
Melee Damage Taken
Player Melee Dmg Melee % Hit/Miss M.Low/Hi M.Avg #Crit C.Low/Hi C.Avg Crit%
Nerji 3627 96.64 % 3735/5550 0/23 0.61 243 0/42 6.23 6.51 %
Passive Defenses
Player Evasion Evasion % Parry Parry % Counter Counter % Intimidate Intimidate %
Nerji 4801 45.28 % 1265 21.87 % 766 17.02 % 0 0.00 %
=1.96*SQRT(0.1702*(1-0.1702)/(3735+766)) gives a confidence interval of +/- 1.1%
Most likely the kabuto only gives 5% counter, not the ~10% stated on the wiki