hmm.. I can't think of any really specific examples right now.. but my Wolf Guard Battle Leader on bike always seems to forget to turn his Frost Blade on, and charge into a unit of MEq's, with 5 Str5 I5 Power Weapon Attacks, hitting on 3's, and 9 times out of 10 he does nothing more than make his ipponents slightly aggravated. However, he does also have a charmed life when it comes to armour saves..
Basically, I have an invincible, but ineffective, combat-monster