Given that Heavy Shields are one-handed weapons normal rules would dictate that you could wield it two-handed for extra damage. However I have heard many people state that you can't wield a shield two-handed. So are there any actual rules stating that Shields cannot be wielded two handed? If so please site the location of this information.
So there used to be this ambiguous rule:
You can bash an opponent with a shield, using it as an off-hand weapon.
As gatherer818 reports, the bolded section was removed in an errata. This is good, as it clarifies how the rule works. However, despite this statement, you could use a heavy shield two-handed even before the errata. Here’s why:
There is no such thing as an “off-hand weapon” under the general rules
The two-weapon fighting special combat option refers to “attacks made with the off hand” which is the closest the rules ever come to using the term. Even there, it is in a specific case, not a general purpose rule.
If you are not using the two-weapon fighting special combat option, you do not have an “off hand.” It is not a general term applied in the rules.
As such, the phrase “as an off-hand weapon” is descriptive
The rules text for Pathfinder is a mix of description – statements which illustrate how things are used – and proscription – rules, requirements, and limitations on actions. It can sometimes be difficult to tell the two apart; this is something that some rules systems (D&D 4E, Legend) endeavor to correct, while others (most notably rules-light systems) embrace by doing away with proscription altogether, but there are nonetheless a lot of systems, like Pathfinder, that use a mix of the two.
Since “off-hand weapon” is not a game-term, and the phrase is used in an introductory sentence for a special combat option, it is being used descriptively – how the author expects you’ll want to use it. The original author of the line, which also existed in 3.5, even explicitly stated this fact. (link pending)
Attempting to read the line proscriptively makes no sense
Both from game balance and verisimilitude perspectives, claiming that a shield can never be a primary weapon makes no sense. This has nothing to do with two-handing the shield at this point, it’s about using the shield as a one-handed weapon, rather than forcing it to be the light one (or worse, a one-handed weapon used as the off hand attack in two-weapon fighting, accruing substantial penalties)
Heavy shields are one-handed weapons when used to shield bash. As such, they have to be the primary weapon, or else you take large penalties in the one case where “off hand” is even mentioned in the rules – two-weapon fighting. To effectively use a heavy shield as a weapon while dual-wielding, you must be using it as your main hand, and a light weapon as your other weapon.
Which perfectly describes the combat style of the Roman legions. Seriously, the primary melee armament of Roman legionaires was a large, heavy shield, and a small, stout gladius – a short sword. The style is more effective when you have an organized formation, of course, but that doesn’t mean it suddenly become physically impossible without that. A Roman legionaire cut off from the legion and forced to fight on his own would still fight that way, because guess what – those are the weapons he’s got, and that’s the style he’s been trained in. And while it might not be ideal, it’ll still work pretty well.
Shields make fine bashing implements, particularly when they’re heavy, which they often are. Their reach leaves something to be desired, and it can make it difficult to use the shield for its primary purpose, but it still works just fine.
Two-handing the shield is therefore allowed under the rules, and also can make sense
Imagine a big, heavy shield strapped to your left arm. You can hold it up to block things, swat at guys a bit with it, but what do you do if you really want to bash someone with it, say if your primary weapon’s been knocked out of your hand?
You’d grab your left fist or wrist with your right hand, and swing with both together, putting your whole weight behind the blow. Certainly seems to justify tacking half your Strength onto the damage to me!
And I’m certain there is ample illustration of this technique from Captain America comics or movies; I’ll try to dig those up tomorrow when I get a chance. For that matter, consider Captain America: he usually fights with a shield on his arm, and no other weapon. He’ll punch with his fist, certainly, but he also fights with the shield. It’s iconic. His fighting style is often very much shield as primary weapon, fist as the off-hand, secondary weapon. Sometimes putting a little more oomph into the shield bash is worth not getting to punch.
A heavy shield, as a one-handed weapon, can be used two-handed for 1.5x Str mod damage.
Wording that previously confused this point was removed in the Pathfinder 1.4 errata available here:
Page 152—In the Armor Descriptions, in the Shield, Heavy; Wooden or Steel entry, in the Shield Bash Attacks section, in the first sentence, delete “using it as an off-hand weapon.” Repeat this change to the Shield, Light; Wooden or Steel entry.
You can bash an opponent with a shield, using it as an off-hand weapon. Used this way, a shield is a martial bludgeoning weapon.
Because it is wielded as an off-hand weapon, it can only be used in the off hand with the typical penalties. As a result, two handed is not possible, and you can only add half strength.
The primary reason I would rule you cannot use it as a 2 handed weapon is that the ruling specifically states "using it as an off-hand weapon". Later, "For the purpose of penalties on attack rolls, treat a heavy shield as a one-handed weapon". This to me says that while you can use a shield for this specific attack, where it is an off-hand weapon, it is not the same as a one handed weapon, and thus the rules around one handed weapons don't entirely apply.