The Blue Spirit putting out firebending with a bucket of water is the absolute funniest thing ever done in avatar combat. It just is.
Imagine after the war it comes out that Firelord Zuko was the Blue Spirit and you, a random former Pouhai Stronghold guard, have the sudden shocked realization that you were once taken out by the teenage future Firelord with nothing but a bucket and a metric ton of stubborn moxie
considering how many times he was defeated by katara, this doesnt surprise me. he was learning from the other elements long before iroh taught him its value