gidgemuffin: they are all different things.

a sigil is the embodiment of a virtue and will always be found above ground. you will just need to find the person who has it.....or knows how to create it. ;-) (hint for later on!)

a glyph is a rune that has been corrupted by the evil forces that have been unleashed by the guardian.

when you take each glyph and the appropriate sigil to each shrine and meditate the shrine is cleansed and restored and the glyph is transformed back into a rune.

don't forget to take them with you after you are done!