You are moving unnoticed thanks to invisibility. You encounter your enemy. Here are your options:
1. Appear suddenly, and explain everything to the enemy. Then give him all the time he needs to think, and plan his next move while you gloat.
2. Stay hidden and cut him down.
Even if you wanted to capture him alive, knocking him out with a surprise attack and binding him would have been way smarter. But because Hermes Familia made the dumbest of choices, they get rewarded with strong resistance, getting held in place to fight this thing, and possibly losing members.
This series is usually better than this.