So, a number of folks have posted angry missives in the official WoW forums over the past few days, excoriating Blizzard for what some have suggested is a “stealth nerf” of the Dancing Steel enchant, the top weapon enchant currently available for rogues.
In particular, people have called out the fact that if Dancing Steel is on both of a rogue’s weapons, it can no longer “stack” — i.e., since 5.1 launched this week, there can’t be two procs active at the same time, which means the effect can no longer double. (Instead, if the proc is already active and then procs again on either weapon, it refreshes the duration of the sole active proc.)
Turns out this is entirely intentional, and probably isn’t nearly as catastrophic for our DPS as some were assuming. (People who play WoW overreacting to small changes with forum tirades? Unpossible!) It's also something that Blizz is working on "fixing," although technically it ain't broke.
Daxxarri's forum posts from last night provide more info: http://us.battle.net/wow/en/forum/topic/7199402840?page=2#21