Sword hijacking
From Halopedia, the Halo wiki
Sword Hijacking is a trick that will allow you to hijack enemies from a slightly greater distance, and at a faster speed. It requires perfect timing and a Covenant Energy Sword.
Walkthrough
This technique is simple enough. Merely perform a Sword Cancel (by holding down the "X" button as you lunge) towards an enemy vehicle. Continue to hold down "X" while lunging, and you will automatically hijack the vehicle when you get near it. This is particularly useful for boarding enemy Scorpion Tanks, Wraiths, Banshees, and Ghosts. It is even more useful in multiplayer.