So Gangplank's Glowing Weapon is the Crimson-Coil Dagger?

I was just re-reading Act 3 when this part caught my eye, "Something gives. I think I cut my hand. The dagger is falling. Into the abyss. There it goes... Is it glowing?"

It makes more sense on the origins where his fiery, magic blade comes from. Possibly even foreshadowing that GP and the dagger are reunited after the events of Act 3.

Now the question is, where does the dagger come from? What makes it glow? Blood?