a)ndrw=n au)= me/g' a)/ristoj e)/hn Telamw/nioj Ai)/aj
o)/fr' )Axileu\j mh/nien: o(\ ga\r polu\ fe/rtatoj h)=en,
When I read these two lines I understood O( to refer to Telamw/vioj.
Every 10-15 lines I check my understanding with an English translation.
This is how I found that O( refers to Achilles.
This makes perfect sense, but when you read Greek as slow as I do, it is hard to use context to determine something like this.