You're right in saying that he triumphs in the cerebral realm; what you missed is that there's something bigger going on. And I have no idea what it is, but I do know from the fact that Sherlock made sure John had his gun on him before they boarded the helicopter that he intended to shoot Magnussen from the very…

Sherlock asked John if he had his gun before they left in the helicopter. He always intended to shoot Magnussen, it wasn't some crazy act of frustration…that's not his style.

The problem is, we just got cliffhung. Sherlock didn't get "bested" by Magnussen- remember how he asked Watson if he had his gun in his pocket? He planned to shoot the guy the whole time, for reasons that aren't clear to me yet. There was also something odd about him insisting that Magnussen repeat that the vault was…