@TheVectorPrime: Thats a nice feat. Although, Magneto would not be able to do anything, if it was composed of a non-metal. Ki is not based of Light. Ki is in-fact Invisible (Kiai, kikoho), in DB they can convert it into light, fire, lightning etc. If Ki was based on light, then many of the cast would be FTL.Ki is life force/spirit. Meaning that Magneto cant manipulate it. Vegeta is no slouch in the reactions side either, he reacts to Android 19's eye lasers. Ultimately Magneto is too slow to land an attack on Vegeta, Mags will be hiding behind his shield until he is overwhelmed.
Yes you're right about ki. Anyway ki blast can be considered like lightning. Lightning is no where near the speed of light to be precise. And some technich are based on light. For exmaple Tien's Solar Flare. Magneto manipulates entire electro-magnetic spectrum and not just magnetic forces. His shields appear instantly. And Vegeta would need to use powerful attack (Magneto's shields endure nukes like if they are nothing) which needs time in order to be charged up. And that would be enough time for Magneto to augument his reflexes.
Ki cant be considered as Lightning either.
However Ki can be converted
into things like, Light, Lightning, Fire.
Ki is also used to augment the body.
Ki can be passed to another person, eg Krillin and Gohan give Piccolo their Ki.
Ki can traverse dimensions/realms, eg Goku gathering Spirit Bomb in Kaioshin Realm.
This is why Ki does not relate to EM spectrum.
This is also why Mags, there for cannot manipulate it.
Akira Toriyama, states that Ki is made up of three components: Genki (元気; lit. "Energy/Vigor"), Yūki (勇気; lit. "Courage/Bravery") and Shōki (正気; lit. "Mind"). < This better explains the concept of Ki.