Paulsen had a fantastic idea for nerfing crossbow, I had a pretty similar idea but never really shared it and didn't have as clear of an idea of how it could work unlike Paulsen (https://www.twitch.tv/videos/336554402?t=01h14m39s fantastic conversation from here). He had some other fantastic ideas to go along with it all in the vod. The problem with the crossbow is that the healing is instantaneous. Every other healing item heals at a rate like the Medigun, dispenser etc. This along with lowering the amount it heals for I reckon would make it a much more balanced weapon without being disgustingly overpowered. Having it heal at the same rate a level 1 dispenser heals at might be a good start.
Instead of loosing a 1v1 with a scout cos they got a lucky arrow shot at them, they would only heal a small amount in the time it took you to reload and shoot, while still retaining the ability for them to retreat and re-heal. It would still keep it usable enough for pocket rollouts etc as well.
Obviously the crossbow needs a nerf, too ingrained in the meta to be banned, and needles are just bad so need a buff (dunno how though).
Just my 2c.
Great video though Nursey.