Welcome to the demigod school

Percy: Hello, for all of you who don't know me, I am Percy Jackson, your instructor. Since this is session one, well go easy, with toy swords.
Octavianspetlegacy(Made up character): Toys, seriously! I thought this would be fun
*Percy brings out riptide, uncaps it, and puts it under Octavianspetlegacy, his neck*
Percy: Would it be fun if I slit your neck?
Octavianspetlegacy shakes his head
Percy that's what I thought. Anyway, the pairs are Persassy 1011 and Frost Bite, Chelsea Delos and Happy Camper, and whoever reads this later can also be paired up. Now lets start fighting. I will show you some basic moves. Can you come here Octavianspetlegacy?
*Octavianspetlegacy walks up, groaning, and Percy gets a toy sword*
Now, Octavianspetlegacy will help me demonstrate a good parry. Stick your sword out please.
*Octavianspetlegacy sticks his sword out, Percy pushes it aside quickly.*
Percy: They key to a good earry is to distract your opponent. Now get into your pairs and try it.
*Everyone gets into their pairs and does good swordplay. Then the bell rings*
Percy: Have a nice day!
Chelsea Delos: You too!

Notes

Question:
What is the key to a good parry?