@Kishido:
I thought about it when he finally joins for good and sails away with SHs.
What can his power ups be besides haki?
Luffy has DF, gears and awakening
Zoro just got Enma and hasn't shown his demon aura aka Ashura since the ts
Sanji just got his RS
Nami got Zeus and can awaken haki
Usopp has gadgets and can learn CoA
Brook has awakening and haki
Robin the same
Franky will upgrade himself
Chopper haki and awakening
But what about Jinbe? He already has haki and is a master fishmen karate user. So
Take a leaf from Kisame and get himself a fancy weapon. I'm expecting him to show up in homie form after having been captured by Big Mom, if only temporarily. Lotsa characters representing yokai, so somebody's gotta play the role of the barbed shark monster known as the Isonade http://yokai.com/isonade/. Based on its description, I could see Big Mom placing his soul in a giant shark skin grater ( an actual kitchen utensil )
https://shop.r10s.jp/sugiyama/cabinet/ikou_20100222/img10033014041.jpg There also happens to be a notable yokai that amounts to just that – the grater-turned-demon known as the yama oroshi https://yokai.fandom.com/wiki/Yama-Oroshi
However it plays or whatever form the homie takes, I could see Jimbe ( after having the bulk of his lifeforce returned to his real body ala Charlotte Moscato ) wielding a homie weapon; be it a separate unrelated one or the very homie that was created using his soul, with a small amount remaining. I would lean towards the latter, as it'd be just unique enough to avoid redundancy on the crew. Plus, Jimbe's already witnessed first-hand the power of the soul connection in action when Big Mom had Prometheus by her side, so might he'll get be inspired to use his new toy as his own virtual zanpaktou lol.
Aside from that, I could also picture Jimbe learning advanced armor haki. I foresee a clash with Sentomarou in the future, so only natural he'd be packing the necessary skill level in haki when he pits his karate/judo against Sentomaru's sumo. It ties into the legend of the folkloric hero Kintaro the Golden Boy ( Sentomarou's inspiration ) and his battle with a giant fish ( played here by Jimbe ). And if Jimbe does gain a giant melee weapon per my theory, he's then also got a counter to Sento's oversized axe.