I would give a slight advantage to the sorcerer.
If you just do the math, the one that starts should win, as the skeleton assassin has two kill points and the sorcerer 4 lives it should take two strikes.
On the other way around its the same equation, 1:2.. however magic never misses, direct attacks can miss.. so slight advantage sorcerer... a hint could also be the 4 to 3 points...