Regarding spirit weapon cosmetic hitboxes
I recently saw this post (https://www.reddit.com/r/DeadByDaylightKillers/comments/1wx0i3d/this_might_sound_unfair_but_what_other_spirit/) containing a discussion on whether or not spirit weapon cosmetics change the hitbox of her weapon. The information that they do change the hitbox came from a video by remylea (https://youtu.be/vdQ9xJuAlyA?t=254) which imo didn't provide enough evidence for this to be true, so I investigated myself.
I positioned a bot both barely in and barely out of range from me (myself at x = 4000, the bot at x = 4176 and x = 4177) and tested (in order) the normal cosmetic, the embellished blade and the putrid katana, which were the two weapons mentioned by remylea.
All three weapons hit with 176 cm distance and all three weapons missed with 177cm distance.
I conclude that remylea's claim is false and all cosmetics do have the same hitbox.