Assuming 6 targets (seems the most fair assumption vs a 6 man party), round one fireball, 5d6 on each. You could get way more of course, or do other things, but regardless, a fighter isn't going to be anywhere close. He needs to make up for it by being an absolute wall with crazy high saves, mobility, AC and combat tricks. Even that wouldn't make up for it in PnP but at least in a crpg where utility is non existent they only have to compete in combat.
Hmm... I'm kinda curious how much damage a level 5 fighter can do, in terms of d6s, with no buffs because the wizard is busy throwing fireballs.
First contender is a half-salamander fighter (+1d6 fire damage to all attacks) with Two-Weapon Fighting and Superior Two-Weapon Fighting (no penalty for non-light weapons), wielding two +1 katanas (Japanese steel, obviously). Let's give him Damage Focus (+2 dmg for all weapon attacks), 18 strength, and Intensified Energy (1d8 instead of 1d6 fire damage). That's two attacks 1d10 + 1d8 + 4 (str) + 2 (focus) + 1 (enhancement) and 1d10 + 1d8 + 2 (half-str) + 2 (focus) + 1 (enhancement) = 32 average damage. That's roughly 9d6, but only for one target.
Since the wizard can hypothetically hit 6 targets with a fireball, let's suppose two of them are standing close enough together to get caught up in a whirlwind by a half-giant (uses large weapons) fighter. He's obviously gonna use a +1 Waraxe (2d8 dmg, -1 atk), but he'll use the large version that does 3d8 damage. He has 20 strength, Damage Focus (+2 dmg), Whirlwind Attack, Improved Whirlwind Attack (+2 dmg on whirlwind), and Fast Whirlwind Attack (whirlwind is standard action instead of full-round). He'll attack two guys, each at 3d8 + 1 (enhancement) + 7 (1.5x str) + 2 (focus) + 2 (whirlwind) = 25.5 average damage per attack or 51 damage total. That's between 14d6 and 15d6.
When you factor in the feats that allow you to sunder (-1 AC for whole battle, cumulative), feint (remove dex AC bonus for attacks from everybody for one round), trip, or disarm (weapons and shields temporarily disabled) as swift actions, I think the fighter could do OK in this game.
Of course, a level 5 wizard could be using Spell Shaping (allies in area aren't affected) and Fire Magic (cast fire spells at +1 caster level) and really be doing 36d6 with no chance of hitting allies.
A psionicist could blow them all out of the water with Energy Cone (50' cone of fire, cold, sonic, or electricity; 5d6+5 dmg) with Energy Sculpting (no longer hit allies), Improved Energy Cone (65' cone instead of 50'), and Energy Specialization (+2 dmg). That'd be 5d6+7 to those six guys for 30d6+42 damage which averages the same as 42d6. Also, assuming 20 int for wizard and psion, the wizard can cast 2 fireballs a day at level 5, and the psionicist can cast energy cone 7 times a day.
http://www.heroicfantasygames.com/FWE/Pages/FWE_Title.htm
