What is the 1st strongest sword in Blox fruits?

I'm curious, could you please elaborate on the 1st strongest sword in Blox fruits? I understand that Blox fruits is a game with a vast array of weapons, but I'm particularly interested in the most powerful sword. Could you tell me its name, any unique abilities it possesses, and how players can acquire it? Additionally, are there any prerequisites or challenges one must overcome to wield this formidable blade? Your insights would be greatly appreciated.