As a tank, you can still deal quite a bit of damage, particularly as a Warrior, but Dark Knight is close. Paladin isn't quite is formidable alone (damage-wise), but they can catch up in a raid when all the right buffs are around. You are expected to tank though, which means that keeping the enemy's focus and managing your defenses is your top concern, with damage being secondary. It's a greater responsibility, which is why people shy away from it. In exchange for that extra service to your party, you get much better que times, as tank is generally the most in-need position to fill. People will expect you to know what you're doing though! It's true for everyone, but it's painfully obvious when a tank messes up.

If your friend doesn't want to tank, Dragoon has a similar aesthetic with mail armor and a big sharp weapon.