Hi Hennie,
have you already done this hike this last weekend? I've been out hiking in the Berg the entire week myself, so I hope this info is not too late.
Corner Pass is not a climbing route, though it certainly is more challenging than the other passes you've mentioned. It is a fascinating, narrow gully that does have parts where you would need to scramble and use your hands, much like climbing Cathedral Peak that you also mentioned. It is generally steep and there is no path. The gully is full of loose stones and boulders.
You may need to take your packs off at some places and hand them up to someone, or pull them up with rope. There is a waterfall roughly halfway up the actual gully which does require some climbing but it is not too difficult and can be done by strong hikers. See picture below:
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Just before the top the gully narrows into a small chimney (rock, soil and grass mixed) but the trickiest bit is probably less than 2 meters.
I've recently been up the pass and that with 2 people that are definitely not climbers and they made it. It was also very wet and slippery at the time, with water coming down the gully. If you have a sense of adventure and can handle some scrambling then you will probably be OK. I would imagine however that this pass could become very tricky in snow and ice conditions, so bear in mind that it may not be usable at times in the winter.