Not sure if you are asking in earnest, but bone damage from a knife would suggest the skeleton was from a murder victim.

They can tell skeletons significantly older than 1000 years were from someone, for example, killed by a tiger, due to teeth marks on bones.

Saw an interesting viking museum in Norway that had a skeleton of a man who had his leg shorn off by an axe in battle. That one may be a bit more obvious I suppose, but I suspect there's a ton you can learn from just a set of bones.

You could probably make a tv show about that, maybe call it bones :-)

Blade markings on the bones, rib cage I believe. They were also able to say the victim was 17-20 years old

Maybe as people who were not murdered were buried in some sort of burial site? (Like a cemetery).

Most likely bone fractures and similar signs should still be visible.