Hi how ppl get +8 head on 2hweap i can craft only +4 do need drop some more legendary scrol to lvl up it ?
Maybe temper again and again and again… until you get +2 on both weapon and offhand. Then masterwork again and again and again until you get the +25% augment at level 4 (and 8 and 12 if you really swim in cash!)
Have to brick lots of gear to failed temper and then burn lots of masterwork material… But eventually you can get it! 
It’s for the truly dedicated! 
But it’s possible! 
+4 is the max you can temper then you need to masterwork the weapon to 12/12 and hit the +hydra head “mastwerwork crit” 3 times which happens at masterwork 4/12, 8/12 and 12/12.
The odds of hitting all 3 are 0.8% so you’re in for a long grind unless you got yourself some big luck.