Neat idea to severely nerf the crafting mats by default and separate loremaster (ennemies and items).
I agree that leadership could affect the character that has it. Originally I was thinking that it should disappear but this buff forces you to pay attention to line of vision (I do not know if it's good design or bad design, but it's gameplay). But indeed it could work for the wearer of this skill, and simply be nerfed a bit (since you give it to the wearer, you improves its efficiency by 33% in a 4 char party, you could nerf by that amount).
