Use Faerie Bladecrafter's power from when it was last on the battlefield to determine the value of X.

Normally, combat damage is dealt all at the same time. In that case, Faerie Bladecrafter's first triggered ability triggers once for each player that Faeries you control dealt combat damage to, regardless of how many creatures were dealing that damage. If any of those Faeries have double strike or first strike, the ability will trigger once for each player dealt damage in each combat damage step.