I have no clue. Just the ideas that swirled around in my head. I don't really pay attention to what's possible in modding when I make a mod. That's how you get awesome mods. Other mod makers just dismiss an idea because they don't think it will work. I pursue any idea that sounds good. Also I know that the whole "tell what book the player broke last" thing is entirely possible. Not sure about extra combat or body examination though.
P.S. anyone who wants me to figure out features for any themed mod (tv show, movie, video game, etc), can contact me at Jtuten1209@aol.com. I will be happy to help.
P.P.S. I don't program mods, I just come up with them.

I think it could work well. Maybe have your player be able to recognize what block any player broke last because of block residue on the hand or something. Also on the shoes, have the last biome the player walked in be recognizable by the dirt on their shoes. Also possibly have it so that mobs bodies don't despawn, and you can figure out what/who killed them along with weapon type. (Bruising would indicate a shovel, cut marks a sword, deep wounds an axe, etc.) Also it would add an extra level of combat to the game by adding "weak points",(Throat, eyes, ears, groin, etc) each having their own effect. Hitting the throat would be a crit, eyes would blind the mob, ears would be like blowing out the ear drums stunning the mob, and groin would drop a mob in one hit however you would have to be one block under the mob. The mod would also include a few extra items to the game such as; cigarettes, pistols, magnifying glasses, and also some more clothing options. (Long coat, Scarf, etc)