User blog comment:Northstar1012/Telling your enemy the abilities of your weapon/@comment-452405-20100330105749

They don't explain because of storyline needs, just to let the reader know whats going on. If Shinji hadn't of explained his ability how many people would've realised what was happening? Injuries appearing on the opposite side it was cut! Sure you'd have your suspicion but you'd never know for certain until somebody in the story explained it.

Might as well get it over with sooner then later, even if its your enemy your explaining it too.