Rayearth's Description

At first, the Knights didn't really understand why they required Mashins to fulfil the legend other than perhaps they could do all the dirty-blowing-piles-of-monsters-away-job for them, but when they saw Zagato's Mashin, they understood (or more specifically, Fuu stated) - since the enemy has a Mashin too. This is actually wrong, and they'll find out when they fight Princess Emeraude's Mashin. It's actually because the enemy they have to face is so strong that it'll be impossible to win without a Mashin.

Zagato's Mashin houses a rather vide and nasty variety of spells which Zagato himself didn't use eariler on. Besides spells, the Mashin also has a long weapon like what knights would use while duelling on horseback in the medieval ages. Zagato and his Mashin nearly destroyed the Knights along with the legend of Cefiro, but just as he was closing in for the kill, the Knights pulled off their combined magic "Spiral Light" which destroyed Zagato's Mashin, killing Zagato in the process.

Facts about Zagato's Mashin