Here is nice info what i find about assassin offhand and general DPS,
Few facts:
- base offhand proc chance is 10% (naked, without gear)
- for every 5 dex you gain 0.1% chance to do offhand damage
- offhand damage proces from Main Hand Weapon , not your offhand Weapon
- offhand damage can proc even if attack is blocked/parried/evaded
- stance damage (+unholy dmg or poison dmg) is added to offhand attacks
Offhand definition:
Offhand damage is an extra damage that can proc from main hand weapon that is used in both combos and white hits.
Offhand damage will proc only once, but for your viewing pleasure it will be broken down into many pretty numbers to clog your screen and stroke your epeen.
In a nut shell offhand damage gives you chance to dubble your damage output.
If SS could be called "the bread" of assassin, corrupting strikes is without a doubt "the butter" for that pve/pvp bread.
For the cost of one soul shard you will get 10 seconds of +20% offhand chance with mere 20 second cooldown.
Corrupting strikes vs Vile Corruption
In order to progress down the corruption tree you need to pick: corrupting strikes or Vile corruption. +15% to slow death strikes is nothing to laugh at, BUT +20% offhand affects your every combo and hit so in terms of "global dps" you are getting suprerior buff compared to just an SDS upgrade.
Corrupting strikes and Dread Weapons (corruption/general)
If you don't pick CS you shouldn't even look at Dread Weapons. Since Dread Weapons proc of offhand, those two feats are "dream synergy" and an conscious design by FC developers.
Corruptiong strikes and Deft Blades (hybrid)
Here is where the source of hybrid power really is: it is not tons of heals and dmg buffs, it it infact offhand stacking that gives 20% + 10% = whooping 30% offhand. Let's compare it to the "offhand build" aka Lotus: we have +10% offhand from deft blades, +15% offhand from flurry of blows (goes off randomly) and +15% from assassination (proces off on targets low HP). So at peak of performance, if everything proces off, Lotus gets 45% offhand whole Hybrid can get 30% offhand without any effort and basicly any time you want it. Deft blades and CS are another "dream synergy" that wasn't really foreseen by the Devs and it might get changed in the future by moving Deft Blades a little further down the Lotus tree (it would require TONS of tests so not to screw the Lotus assassin's early leveling experience). Deft blades and corrupting strikes are MUST for hybrid assassins and a perfect marriage between lotus and corruptin trees.
Corrupting strikes and combos
Offhand from CS affects both white hits and combos (see more on offhand)so if you drop it for combo steps you will get more damage from it. Using CS right before the last combo step is also a good move. The only thing you should NOT do is droping CS right in the middle of combo animation: the combo will get "cooked" and as a result you will go into your casting animation while the combo bar will progress for SS's duration.
Offhand and brutality
Corrupting strikes give offhand chance and offhand can almost dubble your damage output. In order to proc fatality you need damage that will overkill your opponent (more on brutality). Corrupting strikes might give your brutality/normal fatality that extra dmage edge for that sweet fatality procc.
Keep it handy
Since you will be using CS every fight (at least you should) use easly accesibile key that you can press fast and without any effort.
