How about Riposte?

[Shurrikhan]

New Skill: Riposte. When you parry you also riposte. Riposte deals damage per point.
Vitality now increases Parry Chance at half rate as it did before.
(1000 Vitality = 500 Parry)

Pretty sure it was Dex that modified parry (and block), never Vitality? Also, that would mean you'd be hitting for some 700 damage every parry with any sort of actual 'parry build'. This would likely be quite overpowered with high-tier gear, especially when it is carried over during leveling (e.g. FCoB gear from 50-53).

[Nektulos-Tuor]

Pretty sure it was Dex that modified parry (and block), never Vitality? Also, that would mean you'd be hitting for some 700 damage every parry with any sort of actual 'parry build'. This would likely be quite overpowered with high-tier gear, especially when it is carried over during leveling (e.g. FCoB gear from 50-53).

An RNG attack can't really be relied upon.

Also, critical hits add 50% damage to attacks. So critical rate, the stat pretty much makes you hit for 700-1000 more. So, if this is indeed "overpowered" then so is critical rate, infact its more overpowered because it takes 1 stat and not two stats.

[Shurrikhan]

An RNG attack can't really be relied upon.

Also, critical hits add 50% damage to attacks. So critical rate, the stat pretty much makes you hit for 700-1000 more. So, if this is indeed "overpowered" then so is critical rate, infact its more overpowered because it takes 1 stat and not two stats.

I'm not arguing with the concept, only saying that your formula would need some revision for appropriate scaling. One could have as much as ~550 parry stat back in first Coil, which would cause Parry to hit for more than Rage of Halone. During the leveling process the value of the stat would sink back down to much lesser significance because it doesn't scale with our quickly increasing primary stats, and then as secondary stats begin to overtake primary again, and parry more gearable, it would again eclipse the value of Determination and Critical Strike against only quick-attacking physical enemies - a particular gearing annoyance XIV has thus far tended to avoid.

On the whole parry/riposite would still be lackluster; the issue is the massive difference between when it's crap and when it's overpowered. RNG isn't even the beginning of its issues. Magic can't be parried, and the pace of riposite is the pace of incoming attacks x parry chance. That said I still don't what you're talking about in your comparison between Critical Strike and Riposte, which you introduced as a "skill", not a "stat" (hence my thinking that the damage was based on the adjacently referenced Parry... if that is incorrect, I apologize).

(Personally I'd just like to see Parry/Block usable against magic attacks to a variably lesser extent, where DRK can perhaps even (conditionally - e.g. under DM/DD) charge its blade with parried/absorbed magic damage, and PLD could, say... block magic damage while in Shield Oath and parry it while in Sword. The Parry stat would likely then just shift to Reflex or whatever name works for both Block and Parry (the effects being split and/or Oath-dependent for PLD, for whom the stat would otherwise be overpowered).

Back on topic:
Any attempt to make the parry stat relevant has to also be somewhat paired at least with parry even being usable. As it stands, half of our Alex encounters focus on damage that cannot even be parried. One alternative would be to have a corresponding anti-magic defensive stat, but then we would have only one role in the game condemned to piece together sets through horizontal progression to be swapped out with each fight for best results. A better solution would probably be to get rid of the parry stat entirely, in favor of something that works on both physical and magic damage, or revise parry's limitations (esp. vs. magic).