Guild Wars 2

*Sigil of Doom: The number of uses on this skill’s effect will now decrease if an attack lands or if the attack is negated by Blind, Block, Evade, Obstructed, or Invulnerable.
*Sigil of Intelligence: The number of uses on this skill’s effect will now decrease if an attack lands or if the attack is negated by Blind, Block, Evade, Obstructed, or Invulnerable.
*Sigil of Leeching: The number of uses on this skill’s effect will now decrease if an attack lands or if the attack is negated by Blind, Block, Evade, Obstructed, or Invulnerable.

What exactly is meant by this? I might be dense, but sigil of leeching provides a single life leech, so what exactly does this change do?

Sigil Text: “Your next attack after swapping to this weapon while in combat steals some health.”

“Next Attack” means it still effectively has a counter, even though that counter is just one. It just means that if that attack is mitigated by the target in any way that is not just a Miss, it will still reduce the counter by 1, but not actually apply the effect (I assume).