MMm. Wouldn't be so certain about an axe (speaking with the benefit of decades of alpine experience rather than once round the TMB). 'Late' summer, up to end of august probably OK. But all seasons are different, all areas different. Some very experienced friends of mine had very unexpected problems in late June, with extended snowbanks having decided not to bother carrying axes. Can be early snow high up end of August. Soft not hard, passes not snow and ice covered but still awkward. Actually, I remember seeing someones post online of their walkers haute route trip - I think they abandoned it (try googling the name). An axe is also very useful for crossing the occasional gully of wet loose shale where a trail has been swept away. I'm not a trekker, but if I were going out for a fortnight trek in the swiss alps crossing above 1500m I would carry an axe such as the Raven Ultra on the pack. Too light to be noticeable (far less so than those huge loads for camping). Also poles of course, especially with the heavy packs. Best to be safe not sorry.