I have previously made a topic regarding this idea in a bit more detail. Take a look if you want (Skills in 4.x)
As for this…
The way you have suggested can be easily abused and don’t really focus on the actual skill rather on reputation as you only need to kill bad people to skill up.
For people who attack you have to be worse than you are and can’t be farmed as it Must be on an online player as you have said.
Same for sharpshooter, you have to kill bad people to lvl.
This is a skill, it can be practiced in any way necessary. People learn martial arts from watching, training with people, and actually fighting with people. It doesn’t only have to be bad people.
Please make sure that what you are suggesting can still be relevant no matter how much you try to run around the topic.
Leveling up the skills seems more of a task rather than actually practicing the activity.
Many can be abused and almost all of them are gonna be very difficult to code.
Like the sneakybeaky skill. You can simply crouch walk around the same xombie for 5 minutes and you’ll have max skill in no time.
The Survival skill also. Just wait till you reach 48%. Have a chocolate bar that heals 5~10%, then do it again and you’ll reach max skill.
Many of these skills can be abused easily or can more difficult than they should as they sound more like tasks than practice