After recently obtaining Ravager's mufflers +2 of my own, i decided to do some tests of my own to pin down the bonus. It's very clear what the +2 bonus is: doubles the bonus you get from normal restraint.
What's not so clear is how restraint works. Which is what the majority of this post will be about.
Things you should know about restraint if you didn't already:
*Restraint "charges" which when added up directly affect WSDMG.
*After you WS, your restraint "charge" counter resets to 0.
*Delay of the weapon/s you use have an impact on the amount restraint "charges" per hit.
*Ranged attack WS are in no way affected by restraint.
*Only the FIRST hit of an attack round has a chance to "charge" your restraint counter. This means all additional attacks from DW, DA, TA will NOT charge restraint at all. (OAX weapons need more testing if they charge restraint after the first hit)
*If the first hit misses, restraint won't charge even if there are addition attacks after the miss in the round.
Weapons used: Senior Gold Musketeer's Scimitar and Company Sword
As you can see in the 2 pictures the # of attacks vary, but the "charges" stay the same.
Testing:
*I used spirits within for my main WS during test.
*For delays with DW i assumed the -25% DW JT effected the delay, thus the damage also.
*I used several combinations of sword/axe/dagger to obtain data for different delays.
*For the tests i would save 300% tp, use restraint, then count up the "charges".
*10 charges were used in all tests.
The following charts show the data i collected:
Here the points are the % increase from the base spitits within damage:
Here shows the damage increase:
With this i believe we can hypothesize that per a set amount of delay, roughly every 30 delay or so, there's a 1%~ increase to restraint damage. So based on this data, a 482-504 delay weapon should receive roughly 18-19% boost to restraint with 10 hits charged or 1.8-1.9% increase to WSDMG per a "charge" and double that with Ravager's mufflers +2 active.
Further Notes:
*Unclear if OAX hits can charge restraint.
*Unclear if restraint stays the same % increase based on each hit landed or if it gets an additive or multiplicative trait with each successful hit charged.
*Unclear how DW effects restraint and what this means for 2H weapons.