Unusual language? Not entirely sure what is so unusual about it. I know I'm an oddball, but I try to be coherent.

In any case, you are right save for a single detail; Corban's wielding the screw-lance, not launching it.

Edit!: Corrections are as follows - they will address each of your points accordingly.

1.He is raising a crystalline barrier about meteor, yes. However, it is simultaneous with his self-railgunning.

2. The impact did not cause the explosion, the pyrolysis effect happening via the interaction with Corban's blade, the crystal as a heat insulator, and meteors barrier (which was imploded) caused it.