Game Mechanics: Whirlwind not riposting all attacks.

[Versus]

[Tue Aug 09 21:45:16 2011] Your instincts take over as you turn aside every attack.
[Tue Aug 09 21:45:16 2011] Auto attack is on.
[Tue Aug 09 21:45:16 2011] Your fury fades.
[Tue Aug 09 21:45:16 2011] You crush Key Master for 20 points of damage.
[Tue Aug 09 21:45:16 2011] You crush Key Master for 20 points of damage.
[Tue Aug 09 21:45:16 2011] Key Master tries to punch YOU, but misses!
[Tue Aug 09 21:45:17 2011] Key Master punches YOU for 1610 points of damage.
[Tue Aug 09 21:45:17 2011] You have been knocked unconscious!
[Tue Aug 09 21:45:17 2011] You have been slain by Key Master!
[Tue Aug 09 21:45:17 2011] You have lost experience.

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It looks like Whirlwind fades immediately when facing Key Master...?