Combat - Your main hand attacks have a 10% chance to grant you an extra off hand attack. Chance increased further by mastery rating.
Am I missing something or does that feel backwards? Combat rogues are designed to have a slow mainhand (2.7-2.8) and fast offhand (1.3-1.4). I know SS spam will make it proc a lot, but it will be proccing an extra swing with a fast low dmg weapon. I can't immagine that the idea here is to get combat rogues to use 2 slow weps with tons of mastery, since that would devestate the combat potency talent (20% chance on offhand attack to generate 15 energy).
Is the appeal of the mastery supposed to be that the extra offhand swing has a 20% chance to grant u 15 energy? Obviously it will be a dps increase either way and they'll balance the % to make it an appropriate dps increase, but I think it'd be more attractive (and less painfull) as the way sword spec always worked even if they have to cut the % chance greatly.
Back when combat rogues specced fist and sword specialization, it was because the procced extra attack was applied to the main hand. So people would main hand a fist for 5% more crit and offhand a sword for 5% chance of extra attack on thier mainhand and got both bonuses. I'm pretty sure it worked the same for double swords where regardless of what wep procced it, the main hand got the extra swing.
Its a mastery designed to contradict one of their best talents for which speed weapon should go in their offhand. You can't be optimal for both. You either get a fast OH and have the mastery bonus be weak (could do double the dmg with a slow wep), or get a slow OH and lose half of your 15 energy procs (since all of combat rogues OH attacks fome from auto attack aside from shiv) I know people will theorycraft this stuff and decide which end up more dps but it just feels wrong for the mastery to contradict/fight against the design of the tree.
The one last thing I can say about this is that it would make offhand wep speed much more irrelevant since as you move faster or slower you nerf one but buff the other's effect.
Or they could make Combat Potency a PPM so weapon speed is irrelevant in proccing it. *shrug* Having Combat use slow/slow would make loot tables easier, too, since every axe/mace/fist could then be slow.