Fruit development, physical training, and a System: in the end, it all comes down to brains.
He obtains the Sea-Sea Fruit from the start, changing its density to create ice and walk across the sea.
The next day, he obtains the Gourmet Fruit and feeds it to his own fast blade. The bond succeeds, allowing the sword to share the benefits of the fruit.
Step by step, the fast blade devours its way into becoming a Supreme Great Grade Sword.
Kizaru: "Listen to me, little brother Rogge. You haven't wasted time training in useless physical techniques. Just develop your fruit to its absolute limit, and you'll be the next commander-in-chief of the Three Services."
Rogge: No! I want it all: the Six Powers, Three Types of Haki, and the strongest fruit.
The Sea-Sea Fruit, the Gourmet Fruit, the strongest swordsmanship, and physical training: a Marine Vice Admiral for ten thousand years, never working overtime, always clocking out on time.
"Marine Vice Admiral Rogge has made his move!"
"Marine Vice Admiral Rogge has stopped!"
"Marine Vice Admiral Rogge has turned around!"
"Marine... Vice Admiral... has... clocked... out..."
The Ghost Market, Marine Hunters: Rogge, the Sea Devil Marine Vice Admiral, has a bounty of ten billion Beli.