Say I make my weapon out of meteoric, and tie it to slaughter. After 5 slaughters, do I get +5 to my next damage attack?
This is correct.
I have been told that I need to have two more pieces of Meteoric on my armor, and as a Kormyrian a fourth piece, and then I would be able to reach +4 if they were all tied to Slaughter, but I do not think that is correct.
Firstly, no matter what, you can never have more than two of the same material benefit, so the maximum number of Meteoric pieces you can invoke Velocity from is 2 in the same encounter.
Secondly, as you can't have more than one identical Augment at the same time, you would not be able to tie Velocity to Slaughter for both pieces. However, if you had two and tied one to Slaughter and one to Deflect, any time you used Slaughter or Deflect it would grant you the stacking +1 to your next weapon damage attack, up to +5 max.
