If you don't think wounding a general, marshal or ruler is worth the effort you are playing a different game. Knocking out the best tactician in the realm for a few days can be priceless in a war. Ensuring the enemies best army is unable to use marshal settings, likewise can be a game changer. Stabbing the noble that leads that large TO unit, might just give your realm time to reform and boot them out. Wounding is of great strategic value. The risk of execution offsets the fact that infiltrators can make such a huge difference as a single character.
