QUOTE(Sapo84 @ Oct 17 2016, 07:32)

It's not 6-7% damage, it's 6-7% clear-speed.
Clear-speed != damage.
And nope, 12M (actually 2k hath are ~11.5M but whatever) upgrade will not get anywhere near 6-7% clearspeed.
Even fully forging a rapier from 5 to 100 (95 BoS)(you can get more damage from power armor, but you need actuators there, so the price is higher) will give significantly less.
Here's the math.
My current damage is 10520 with rapier forged to 75 (2301 damage).
Scaling back the forge to 5 it will decrease the damage to 9822 (1603 from the rapier).
9822 X 1.1 (10% damage perk) = 10804.
9822 + fully forged rapier (2404) = 10623.
With the added bonus that the perk is permanent.
If you forge just one equip, that's what happens. But a player will probably forge more evenly across all Power Slaughters + rapier, which means significantly greater damage for that (2k-hath-equivalent) spent.
What proportion of ADB is added by equipment for 1h heavy, anyone know? If equipment accounts for half of total ADB, then by forging all equips to 11, your weapons get *1.21 damage, which will give you an overall damage boost of about 10%, same as the perk.
Forging all to 11 costs a bunch of actuators and slaughters, about 1.9m + 4.5m = 6.4m worth, plus a tiny amount from HGM and catalysts, which comes out to significantly less than 2k hath = 11.6m. (Assuming someone forges evenly across all gears, which is not a good idea. rapier > armor > leggings etc.)
So maybe light forging is good, but past the first handful of Slaughters used, I'd prefer the first damage perk instead, for its permanence.