Kim and I returned to Tresidder Peak to climb the South Arete. While the standard route (assuming there is one) probably ascends from the west, we attempted the south face. Annotated route photo is here.
Actually, the standard route doesn't start on the west side. It starts at the same place you started, climbs the open book (what I called a chimney, but is probably somewhere in between) to where you show the belay spot. From there you cross over to the east side, where you can continue class 4 climbing up blocks to the summit.
I think what you climbed can be described as a more direct route, and you ought to make a new route page out of it. I'll rename this route the "South Arete: standard route"
Dude, that looked harder than class 4 to me! I thought the open book was pretty tricky, at least 5.4. But I stemmed it, instead of chimneying. Welcome to the Sierras, I suppose. :)
We'll probably go back and get it sometime this summer, so I will do a route page once I climb the upper section. I'm kinda mad at myself for wussing out, but the chockstone I tied off to was such a convenient bail point. If I'd have had to leave one or more pieces behind, I probably wouldn't have bailed.
How did the approach from the summit ridge (NW) look? Getting to the ridge looked OK, but there were some pretty big blocks to traverse. I'd have thought this was the easiest route.
Like Cathedral, Tresidder is rated class 4 from the old days. This discussion goes into a little more detail, but you're right that today they would be rated something like 5.4. For almost all Sierra peaks rated class 4, they are probably more like 5.[1-4] today. I've decided I can't really tell the difference anyway, and treat everything in the class 4-5.4 range as essentially the same. (I think you can easily die if you fall on anything above class 3.)
The east side was what I had tried first - I was doing pretty good but ran into the last problem, about 20 feet of diagonal traversing that would have taken me to the blocks I eventually climbed to the summit. I'd like to go back and give that another shot someday. The NW route from the ridge looked impossible to me, so I continued around the west side to the south side. Maybe I missed something, but it didn't look feasible to me.