Actually I think that Jet Gatling Gun (Gear 2) is probably his strongest attack at this point in time, as that's what he used to beat Rob Lucci back in Enis Lobby.
SonicKing2004
2021-12-31 12:35:23 +0000 UTC
As I understand it, Luffy fully intended to sacrifice his arms to the poison, maybe amputating them just so he can save Ace. I also don't think he's fully thinking ahead but when he said "Give you my arms" he meant that somewhat literally.
Veritas
2021-12-31 03:33:17 +0000 UTC
Rob Lucci said using gear two is harmful to Luffys body. I think Jet Bazooka (gear2) is the strongest attack after gear three.