For me, it's got to be the mind-control nanotech.
The advanced-but-rubbish computers are a bit irritating, but they're needed to let the cast punch buttons dramatically and make the prolonged missile-counting scenes a bit more human. The interstellar logistics fall over when prodded at closely, but all those tramp freighters and shipping lines make the universe nice and busy.
The nanotech just doesn't fit - they can't make decent AI or even smart control software given tons of molycircs, it takes months or years to get used to replacement limbs, but you can puff a few nanomachines up someone's nose, monitor what they're doing accurately, and then produce fine motor control on demand?
As I wrote in my other post, Honorverse automated heuristics are
pathetic - computers seem unable to recognise the most obvious and predictable things without human intervention - when implemented on a shipful of known hardware with purpose-built sensors. But you can reliably trigger this nanotech while reading information out of a human brain with no setup and no storage space and as much computational hardware as fits in a puff of vapour.
Oh, and the unfakeable tongue-barcodes. We're repeatedly told they have molecular-level construction, nanotech assembly, regenerative growth...it doesn't
matter how it's coded for genetically; if you can build things down to the atom you can fake it anyway! Since most people just
look at the things, you don't even need to do that.
