This is totally not a big deal, but just wanted to point out. It appears that Common quality runes are supposed to only give a chance for Binders when salvaged at the same tier level of the rune. For example, a Lesser Common rune has a chance to give a Lesser binder when salvaged. For Uncommon and better runes, you have a chance to get a binder at the same tier and one tier better. For example, if you salvage an Lesser Uncommon rune, you have a chance to get a Lesser or an Improved binder.
This appears to be the case for all tiers of runes except for Improved runes. Improved runes, even Common ones, are showing that there is a chance for a binder at the same tier and also one tier better. I don't think this is intended so wanted to point it out.