As far as i remember they said that he split it.Using some energy beam probably.The reason why Alcanphel is weaker is because he was attacked by the Uranus,not so much by destroying the meteorite.But still it's unclear whether he's weaker than before,because he was then processed in the tank on the Silha island.
I've been always wondering after watching some of the episodes of the 12 ova series.In the end of some of them there were description of the various creatues(for example Guyver 1).And they look exactly like the new Guyver toys.Don't you find that weird?After so many years releasing those toys,or maybe at that time they were just prototypes?