I've paged over a few of the other parry threads, but I haven't seen much in terms of parry pertaining to what a boss does to you. I was trying to figure out a ballpark of how much more damage one would take as a DK that was DWing and tanking, compared to tanking with a 2hr. Primarily to prove a point to a friend, but I ran into some issues on how exactly the parry mechanic works.

So, say a boss attacks every 2 seconds. According to WoWWiki "When you parry an attack, the remaining time on your current swing is reduced by 40% of your weapon speed, unless this would result in a reduction to less than 20% of your swing time remaining"

This would mean that the boss's swing would be reduced by 1.2 seconds each time it parried, unless it was .4 seconds away from the next swing, correct? Or am I misinterpreting this wrong? Or is WoWWiki misinformed? Apologies if this is mentioned somewhere, I looked but did not find anything.