Every spearo needs a tool kit and spare parts. You don’t want to miss out on a dive, just because your gun rubber snapped or you’re lacking the tools necessary to fix it.
Important spearfishing tools include a crimping tool, an insertion tool and silicone spray. You also wanna have some spare parts, like powerbands, rubbers, crimps, monos, etc.
Obviously these spearfishing tools & parts only help you out, if you know how to use them. So make sure to spend some time on learning, not only how to operate your speargun, but also how to take care of it.