What to do with low intelligence champions?

strength and the bow's damage affect bow damage as far as I know

Research adventuring. Choose the dungeon crawling line that unlocks the square hut quests. Do the 'filthy warlock' one. Reward is a potion which gives 0.5 essence. Have a non-caster hero drink it. Kill two wolves. On level-up, put points ino essence.

Voila, a caster! :p

Non-caster champions = gophers.  Go get this goody hut and bring me back the stuff while I do more important things.

And we have a winner

Strength champion makes good archers, it's actually an extremely cheap tactic against a non-range enemy. Go into battle, shoot, then once the enemy gets near, run away. Repeat battle until all enemy is dead. It only because you haven't needed to do this yet that they seem somewhat useless.

Don't forget to pop the attack bumping items on the archer hero. Between the +1 attack ring, +2attack amulet, and the berserker one with +3 attack, -3 defense, that's more attack bonus than the Bows themselves. Throw in a mount and items to get attack speed and....

I have taken in a high dex/str champion and make him my Sov's personal bodyguard with all the best melee equipment. 

On level up I increase HP and Str/Dex on a round robin rotating basis.

For others if they have a city stat like increases food/farm production by 20% then I park them in my best food producing city and they become the head of the department of agriculture, and also an temporary champion equipment warehouse to trade items amongst other hero stacks. 

I was actually going to make a post on this suggesting that the "Mêlée" Champions get a replacement for mana called "Stamina" for using "Mêlée Abilities" like the Brutal Strike or whatever it's called. Basically for exactly what you said. Before the latest patch I didn't see many Champions at all with the Mêlée abilities, then I finally saw one I could hire that had one but he wanted 600 something Gildar to join me. I saved it up and hired him, but then noticed after I had hired him that his Int was incredibly low and I couldn't use the ability because it needed mana to work.

It made me wonder why a guy would even have a ability he couldn't use. Hopefully in a later version they'll address this and separate some of the "Fighter Type" abilities like the specialty strikes from the magic spells and abilities that use mana. You might want to consider refining this and making a post over in the idea's section .

It's an undiscovered ability that only you as an All-Mighty/Incredibly Frail channeler can see the potential for and release.   Besides, have you seen the animation for the "Melee" powers, "I'll smite you with all the strength and power granted by my liege. Quiver as I smash each testicle into different counties." - Raise shield into air, don't swing weapon, stand perfectly still......... there take damage..... Might as well be magic

Also, another thought, Low Int casters are still useful as mobile Settlement Enchanters, Land Sculptors and Summoners. All things currently unaffected by a low int score., and mana your sov can save for trashing enemy units

saw a hero with the warlord trait... (some gladiator...forgot name)

what is the point of that in the sandbox? it ain't going to spawn 2 sentinels of decent strength, is it

Well, that's a good point and all, but when I looked at the ability when I saw it on the champion the description really made me think it was a mêlée attack. I believe Sions have the same ability and when I've used it I always look at what's being hit instead of them using the ability. I think they have to be standing right next to the target to use it as well (we might be talking about different abilities here) which made me think it's a mêlée attack since you have to stand next to them to hit them.