Started watching Yu Yu Hakusho on blu ray now, about 10 years after I first saw it as a kid. Wondering what happens to Yusuke's various power equipment. I recall in the first few episodes he needs some kind of ring/band that helps recharge and focus his spirit engergy for spirit gun... then it just goes away, at least in season 1. Does he still have them?
The devices start to lose their usefulness as the series turns into a fighting series. Being able to track a demon or have X Ray vision aren't terribly useful in a fight against Toguro or Sensui. As for the ring, apparently it makes Yusuke severely exhausted after he uses it; I recall him passing out after he uses it against Gouki and needing to be picked up and brought home by Boutan. He needed it early on when his own spirit energy was fairly weak, but later on, after he trains with Genkai and starts to gain power, the tradeoffs of the ring become more of a liability than a benefit. Presumably he still has it, though, he just doesn't use it because it's not helpful.