Found kind of a bug in Singleplayer; take a Slime Mount and the full Sandstone Armor set, and when you double jump, the sheer landing force instant kills you at Base HP. It's a bit frustrating since I can't use Slime Mount and Sandstone Armor effectively.
This actually gives me an idea. I personally think that if you give yourself higher jumping ability, it's your responsibility to manage it properly. However, I do consider the Zephyr accessory to be a bit pointless as it stands, with all of the other things that can increase speed - particularly any of the sprint boots. If it had, not full fall protection but the ability to let you fall farther before you take damage (basically, treat falls as X% shorter), that would make it a lot more useful.
Though...I'd also accept making it an alternative to the Anklet of the Wind in making the Lightning Boots (or an ingredient with one of the Cobbler's boots to make one or more forms of sprint boots, come to that).
EDIT: Actually, I personally don't get much use out of the Cobbler, simply because the Vanilla boots are so good. I'd love to see more content based around the boots, to make them more of an alternative. For instance...
Zephyr + Steel-Toed Boots: Perseus Boots, +2 Defence, Allows the wearer to run super-fast.
Perseus Boots + Strange Alien Tech: Hover Boots, As Perseus Boots, plus allows the wearer to glide (like the Flying Carpet and Hoverboard).
Rocket Boots + Turbo Boots: Mach Boots, Combined effects of both, plus the ability to dash by double tapping a direction (no damage to mobs, but high knockback).
Slag Stompers + Lava Waders + Molten Scale: Dragon Jackboots, the effects of all the included, but with complete immunity to lava.
...just as some examples.