The term ‘leashless’ goes back to the early designs of ice axes where they all had straight shafts. Without a leash, it was almost impossible to grip and hold the shaft on steeper ground without sliding off the end! The leash was as important as choosing the best ice axe at the time.
Even when the designs of ice axes developed over the years and we saw slightly bent shafts, the leash was key in being able to climb steep ice. There was almost more design and technology going into designing the leash as there was in the ice axes themselves!
Then came fully curved shafts with a heel spur or grip rest on the end, to help rest the climbers grip onto, stopping your hand slipping off the end and in turn allowing you to climb steeper ice with less energy. At the start of seeing the grip rest, climbers still mostly used a leash for added security. But over time peoples confidence grew and climbers started to enjoy the extra freedom and challenge that climbing leashless presented and leashless climbing became fully embraced.
The next big development in ice axe technology was a tilted and ergonomic hand grip, attached to the bottom of the fully curved shaft. On steep ice this allows you to use more of your bicep and back muscles, meaning it is more comfortable, more secure and less tiring as you can 'fight' for longer, before that eventual ‘pump’!
It has now become the ‘norm’ that you ice climb leashless.
But to be clear, people mix up the term ‘leashless’ as there is a also a modern leash!
This modern leash or tether, is typically two elasticated strands looped through your harness belay loop with each end then clipped to the bottom of your ice axe shaft. Elasticated, so the leash can stretch as you swing your axe, and then contracting, so they are not too long to get in the way and loop around a crampon. The two ends of the leash clip either to the bottom of the ice axe shaft or the bottom of the hand grip so that you’ll never lose an axe if you were to drop one.
Now, it’s very rare to drop an axe, but it is possible. If you are leading and you place an axe above and to one side of you then let it go to place an ice screw, a chunk of ice from above could fall down and knock the axe out. Or, whilst at a belay stance, if the axes aren’t clipped to you then it is possible, that pulling ropes about, you could lift an axe out and drop it down the ice.
It is more easy to drop an axe if you are seconding if it is not clipped to a modern elasticated leash, as the lead climber cannot always see the second, especially on steep ice, and they are belaying over the top of the flow or maybe to one side. The second stops, places an ice axe out to one side, then lets go to take out an ice screw. Whilst the second is unscrewing the ice screw, the lead climber ‘takes in’ firmly, the ropes tighten, to secure the second and perhaps, unseen, by the lead climber, one of the ropes is perhaps either running over or looped slightly under the placed axe out to one side, and as they pull the ropes tight, one of them lifts the axe out of the ice and it drops down the ice if it is not secured.
The modern ice tools are leashless, but we still use leashes or tethers!
That’s why Petzl has very cleverly designed a modern ice axe, which has a curved shaft but with an older style grip rest. It’s not a step backwards, as they already have very specific steep ice climbing tools with the Ergonomic and Nomic. This new ice axe is designed with that 90% of mountaineering terrain in mind, as the grip rest folds up and out the way. This means that the climber can plunge the axe into the snow to get the security they need when accessing a climb and then have a very competent axe to climb the steep ice with.
So leash, to leashless....well almost or sometimes!