Dancing Steel - Permanently enchants a melee weapon to sometimes increase your Strength or Agility by 1,650 when dealing melee damage. Your highest stat is always chosen. (12 second buff)
Windsong - Permanently enchants a melee weapon to sometimes increase your critical strike, haste, or mastery by 1500 for 12 sec when dealing damage or healing with spells and melee attacks. Requires a level 372 or higher item.
At first glace, to the average druid who HASN'T been reading along, (jk) Dancing Steel looks to be the better choice.
Windsong (2RPPM)
Uptime 40%
Ave Stat Weight 0.0243 (Crit+Haste+Mastery)/3
Enchant Weight 14.56
Dancing Steel (1PPM)
Agi 1650 %Uptime >14.56
This works out that Dancing Steel needs to have a 30.23% up time.
Time to start watching logs, I will update you guys as I see more actual uptimes from mine and other bear logs.
Note: Basic math:
Enchant Weight = stat weight * amount * % Uptime