I would argue that whip/flail is one of, if not the best choice for primary weapon on an orc for these reasons: They are hard to parry in general, and if you look at the classes that learn both:

Flail:
Skill: Anti-Paladin , Lvl 1
Skill: Berserker , Lvl 1
Skill: Healer , Lvl 1
Skill: Shaman , Lvl 1
Skill: Warrior , Lvl 1

Whip:
Skill: Anti-Paladin , Lvl 1
Skill: Berserker , Lvl 1
Skill: Conjurer , Lvl 1
Skill: Healer , Lvl 1
Skill: Invoker , Lvl 1
Skill: Necromancer , Lvl 1
Skill: Ranger , Lvl 1
Skill: Shapeshifter , Lvl 1
Skill: Transmuter , Lvl 1
Skill: Warrior , Lvl 1

Only AP, Warrior and Berserker learn both. They also learn every weapon Bereserkers do, so there isn't much there. You want a hard to parry/dodge weapon because you tank like ####, so you have to outdamage your opponent.

Also, something which you seem to be ignoring is that you have to be either free offhand or be using a banner. Either way, you loose out on offhand parry, and loose in the offense category compared to (for example) an offhand axe.

Headbutt injures you. It isn't much (comparatively), but whether you hit or miss a lash, you aren't taking any damage. And "Headwear for both attacker and target are taken into account for purposes of damage and chance of stunning." which makes it pretty hard to figure out how reliable it is going to be.

Headbutt has the same size restrictions as bash, actually slightly more since you can't headbutt something bigger than you at all, while you can still attempt to bash.

Finally, this: The following round the opponent gets a bonus to hit the attacker if they were unsuccessfully stunned by the attack.

So, to recap, size restrictions, giving up offense and defense of a dual wield, increased chance of getting hit if you are unsuccessful which is determined by a nebulous gear factor like cranial only more so since your helm factors in, and hurting yourself. Why do you think you *would* use it when lasher makes lash reliable (plus -morale)?

Tac