Your Nobles can assault any other Noble they interact with, after threatening them. If you successfully assault someone, they get "wounded" for some time and become vulnerable to ''capture''.

If they have no weapons equipped then they use their fists and the damage done is slight. You can find and equip weapons ranging from a club to a sword, with each weapon dealing different amounts of damage for different durations and some with bonus side-effects.
  • Summon your Noble in the desired location
  • Tap on them and tap "Interact"
  • Tap on your target Noble
  • Greet
  • Threaten
  • Assault
  • Then you can continue interacting with that Noble and "Capture" them
You can also "Capture" Nobles by successfully attacking another player's Keep!
Capturing a Noble will have them jailed in the Dungeon of your keep. Usually Marshals are the best role for that based on their talents, but don't forget that traits also play a part of the success rate of those actions.