Blade inwards towards the plate is always the table setting instruction for the knife. None of these little details are without having been reasoned through by one society or culture. Many have very practical explanations. For example, the oft under-regarded knife placement:
"... protocol decreed that the blade of the knife to the right of the plate was turned inward. This was not for aesthetic reasons, but for safety. The guest of honor, possibly an enemy and perhaps a would-be assassin of the host, would be seated on his host's left. If the sharp blade of the guest's knife was pointed outward, then that person could pick up his knife and made a quick hard thrust to his right, easily plunging it into the hosts heart in one stroke. If he were forced to twist the blade from the inward to the outward position, his actions would be conspicuous, easily seen by the host's bodyguards, who could deflect the blow in time. That is why, many centuries later, the sharp side of the knife blade in our place settings turns toward the plate."
- Taste, Letitia Baldridge (2007, St. Martin's)
Yes, indeed. Blade in, to avoid being stabbed by the guests! I always say.
Photo credit: Southern Accents