>>2850718There are essentially 4 parts to this route.
1. Hike up to Wedgemont Lake. This is just a steep forested trail. It is extremely popular, many other people will be on it.
2. Hike from Wedgemont lake to the summit of Mt Cook. This is easy, there is a boulder field but the boulders are small and there is an obvious "trail" through it.
3. The ridge traverse from Mt Cook to Mt Weart. This is the knife edge ridge. A few class 4 moves, one of which is a somewhat intimidating downclimb, but mostly class 2-3 scrambling with significant exposure.
4. The descent from Mt Weart back to Wedgemont lake. This descent is not technically difficult but it involves descending a very loose boulder field that is unpleasant. Personally I fell on my ass a couple times descending this.
If you are unsure of your ability you could just summit Mt Cook and decide if you want to do the rest when you get there.