Gin has no named attacks, but is a skilled warrior, a match for even a skilled martial artist like Sanji (although Sanji was severely injured during their fight due to the beating he received from Pearl and Gin was still feeling the effects of starving to near death and 3 days of holding in a prison cell upon Fullbody’s ship). The Baratie cooks’ first impression of him was due to him being starved and weakened; they believed him to be a mere lower-ranking subordinate, until he revealed his true strength later in battle, which led to the surprise of many.
Gin was a man who was captured by Marines upon his first appearance, but after being starved to near death and 3 days of holding in a prison cell upon Fullbody’s ship, he was still able to escape and hold off 7 of Fullbody’s men. He was also able to pin down Red Leg Zeff, a retired yet still powerful former pirate, and broke his peg leg.
Gin seems to be proficient with firearms, as he shot Lines from the back with a flintlock from a certain distance, and held a shotgun at Zeff while taking him as a hostage.
Despite this, his weapons of choice are a pair of tonfa tipped with heavy iron balls presumably the same size as cannonballs. Combined with his own abilities, Gin is a very deadly opponent when using these, as shown when he smashed Pearl’s iron shields with a single blow while moving so quickly that he took Pearl by surprise.
This is a testament to his strength, as even Sanji could not make a scratch on Pearl’s shields. The tonfas act like hammers, gaining more power from Gin spinning them by their handles and building up momentum for his swing.