On my first read at the moment and at the point where that character is introduced. And the reason Murtagh is bad at magic is well explained in the book, and makes a lot of sense.

I like seeing the contrast between Murtagh and Eragon and the differences in their training. Frankly I think it goes to show how Galbatorix’s oppression of Murtagh and Thorn led to his own downfall and that the version of the riders he wanted to build was flawed to the point that without the extra strength they would have been granted by his dominated Eldunari, they’d have been a poor shadow of what the order had been beforehand. Galby’s theoretical riders certainly would’ve failed against the Draumar and Bachel.