So... that spiderman shirt... (new job tease)

[KHMarie]

Snip

Like you can see, that I did post that in an earlier reply so I am aware. :^)
Once more your post does nothing to prove nor disprove him being a Blue Mage. His acquisition of the weapon is irrelevent, as it has nothing to do with how he obtained it and everything to so with what the meaning of the name implies. He could have pulled the sword out of a dodos ass, and it still could mean he is potentially a BLU simply because the blades name is Tizona and his name is Raubahn. No matter how you look at it, even if the person he took the weapon was was a BLU, it still doesn't mean he couldn't be one himself. Look at the abilities he uses in the Eorzean Alliance, because that more recent stuff is more accurate to go off of. He is literally using a move similar to Ifrit's nails that purposely showcases the name of the weapon. I find that hardly to be done without reason.