Gear
When I was young, I was really clueless about "gear," including what was out there and how all that stuff was typically used. I was constantly hearing older, more experienced players chastise younger players for worrying about what strings, amps, guitars, and so forth, to use. As a result, I sort of continued to be blissfully ignorant of such issues for a long time.
Eventually, I began to feel like a complete idiot when I'd get together with other guitarists and listen to them talk "shop." I'd feel totally lost and be so embarrassed about my utter lack of understanding of gear-related issues that I'd just nod and smile, not ask any questions, and hope to catch a glimmer of information here and there.
Over several years, I forced myself to became much more savvy about gear; at some point, I just broke down and started asking questions whenever someone talked about something I didn't understand. I have finally come to the conclusion that, while it's certainly a mistake to think that having an expensive archtop or pedal is going to make you play better, a jazz guitarist, like any other artist, needs to have a working knowledge of the tools of the trade. Sure, I think that, ultimately, a player's "voice" comes from some unknown place deep inside and that all the music theory and fancy gear in the world won't make up for a lack in skill, however, I don't think it's a bad idea for a young musician (or an old one) to spend part of his/her time thinking about the nuts and bolts of how to use the physical tools (and which tools work best for the purpose) to make that inner voice come out as purely as possible.
These days, of course, you can find a glut of gear-related videos on YouTube, but I have noticed that very few of these videos are made from the perspective of a jazz guitarist. As a result, I think it can still be a bit daunting for someone interested in jazz guitar to find information about guitars, amps, and pedals that jazz guitarists use and explanations on how to use them. I think this has contributed to some jazz guitarists having an attitude that learning about gear is somehow dishonorable or that it focuses on the wrong thing. We've all heard the cliché, "The sound is all in your fingers, man!" While this may largely be true, the fact remains that guitars, guitar construction materials and techniques, strings, cables, effects pedals, and amps all play a significant part in a jazz guitarist's sound and aesthetic. I think it's a mistake to discount gear entirely just as much as it's a mistake to use unbridled gear-obsession as a substitute for practicing.
Researching the gear your favorite guitarists use can be helpful in discovering what's out there, as long as you are willing to spend the time to refine and sift through that information in pursuit of finding your own sound.