Correct Woltz. It should also be noted that the novel tells us that Fredo carried a gun. Because of that I assume that Fredo also guarded Vito. Now, the novel also states that Luca carried a gun and his license to do so had been extremely expensive. So, if Luca had such an expensive gun license, Fredo also had one, right? Why spend so much money on securing a gun license for Fredo if Fredo was viewed as a rather ineffectual soldier, Capo, or whatever?

It's true that Vito speaks in a deprecating way about Fredo, but only after Fredo goes to Las Vegas. Again, in the novel, Tom asks Vito if he should call Fredo back from Vegas (I forget why), but the Don sarcastically retorts that his wife can still fix our meals. On the other hand, when talking to some of the other Dons' at the Dons meeting, the novel states that Fredo had a genius for running a hotel and the Don spoke of it it with some degree of pride because it was an unanticipated type of genius in one of his children.

Puzo's writing was indeed confusing sometimes.