As for Wyll, there is no problem once he grabs the Moderately Armored feat at level 4.
Personally I'd rather take Armor of Shadows eldritch invocation than moderately armored since it scales better and is a warlock exclusive ability.
That aside, his AC is less of an issue than the fact that he's hyped up to be an awesome swordsman despite the worst at it (except for Gale, who seems pretty comfortable where he is.)
Also waiting until level 4 is a lot to slog through if you're looking for more than just an AC boost.
