The thing that is odd about will boosts is that the only class of companion it really benefits is Witchdoctor since, presumably, they are holding a weapon that gets a boost from will. Privateer-type companions, for the most part, are holding slashy weapons and, in some cases, slashy/shooty weapons. That being the case for them, the only thing that will would effect are their powers, which companions use infrequently due to them having only one or two. That's why I like the Witchdoctor spell Juju: it just buffs each character's main attribute. That's a cool ability.

As it currently stands:

Privateers get will boosts, which helps boost their heals and barrage attacks.

Buccaneers get strength boosts, which is supposed to boost their attacks, although Kobe Yojimbo, the first companion is a swashbuckler, so he boosts with agility.

Swashbucklers get no stat boosting cards!

Musketeer gets agility boosting, which boosts shooty attacks.

Witchdoctor gets Juju, which is totally awesome, it boosts each class to their perspective boosts.

Now, while you may want this or that, boosts in my opinion are bugged and not working properly, so it really does not matter. On my Buccaneer and Musketeer, I have casted all 3 boosts for their perspective classes and have over a majority of the time, hit lower than I do without casting a single boost.

Prime example, I will cast whales, then sharks, then squids on my buccaneer, after doing this, I average around 221 damage per hit. When I dont use any boosts at all, I usually average around 248 per hit. Now, how does that add up? 3 rounds to boost and hit lower. So, dont concern yourself too much about the boosts, they dont contribute as much as you think they do.

I am not the only one that has experienced and witnessed these effects, many of my friends have all noticed the exact same thing, so it is not just my opinion or my claim, many others can back me up. Most of us have stopped using the boosts, unless there is nothing else to do that round.