I had a friend fall off the Aonach Eagach in winter. Luckily we were roped up, alpine style and I was able to jump the other side of the ridge and hold the fall. He ended up hanging upside down , rope twisted round his leg, over a big drop. It is not a place to take a novice (you have just met) in winter . Any new climbing partner it imperative that you get to understand their abilities and experience. This means a first trip on ground where a mistake is not likely to be fatal and you can get to see each other in action. Did you actually agree beforehand and during the crossing that you would all stick together as two ropes? Why did you only find out they were a novice and ill equipped once on the ridge?. I will always discuss with a partner who is carrying what and the plan before a winter ascent. Descending the Clachaig Gully has not been recommended for years, not even in summer. It has been the scene of many a rescue plus fatality. It is much better to continue down the ridge where it broadens out and provides an easy and safe descent to the road.