I want to empower the Ebony Blade, and I understand that means I need to kill NPCs that trust me, but I don't want to miss out on any quests or advantages. Several NPCs will become followers, merchants, marriageable, etc. on completion of a quest, and in some cases killing an NPC will affect other NPCs. Which NPCs can I safely kill to empower the Ebony Blade?
This isn't a quest, but I'm trying to get a good two-handed sword and I like this one the best.