Thanks for the chapter!
Seems like dear brother is just as spoiled, arrogant, stupid and emotional as his mother. Considering he was beaten by trained bodyguards how did he heal so quickly? Or has several months passed between the beating and now that haven't been noted? Also, even if that is the equivalent of a voodoo doll, shouldn't the pins make him hurt in those places rather than muddle his mind? Elder brother really doesn't consider what he says just like his mom as I'm pretty sure incest, especially between two siblings from the same mother and father, is really frowned on. MC should be telling Zirui that elder brother is an example of a bad child and should be observed on how NOT to act. Bishamonten is the Japanese version of a Vaiśravaṇa, and denoted as a god of war that punishes evil doers. In any case, big brother has apparently been overindulging in vices and shirking his studies and responsibilities while being enabled by his Shenshi. Being a prince means that interrupting him, rudely stating he's wrong, or interrogating him can be construed as elder brother did could be construed as an insult to the imperial family and treason with punishment up to and including not only his death, but that of his family or clan as well.
Was the slap noise after elder brother interrupted him slapping the prince or vice versa? After all, it was mentioned earlier that the prince used a whip to punish a guard and several others for looking at his legs too long when he returned as a whip would extend his reach due to being chair bound by his broken legs. In any case, Feng family will have to endure the insults and reproaches from the prince, beg for elder brother's life to be spared, and likely pay a bundle in compensations for the insults. As for elder brother he's likely going to be whipped and punished severely, and will depend on prince's whim whether he lives or not.