Taco had this very same question last week. We both sat down and read the rulebook. Apparently in Belegarth there is a distinction of blade length, but not in Dagorhir. Here are the Dag rules:
4.3 - Red Weapons
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4.3.1 - Red melee weapons are long hacking and smashing weapons intended to be used primarily with two hands.
4.3.2 - A swung weapon (sword, axe, mace, glaive, halberd, etc.), 48 inches or longer is considered a red weapon when swung with two hands
4.3.3 - A red weapon used with one hand counts as a blue weapon for damage
4.3.4 - Red weapons may have green stabbing tips.
4.3.5 - Red weapons go through armor on the first hit when used two-handed
4.3.6 - All Red weapons when used two-handed can destroy a shield with two solid blows from their legal striking surface (e.g., a solid hit from the haft of a glaive would not count). Blows which are mostly blocked by another weapon and light or glancing hits to a shield do not count as "shield breaking" hits. The fighter wielding the shield judges if the blows are solid "shield-breaking" red hits; however, the physical size of the fighter delivering the blows must always be considered; i.e., a "solid" hit from a smaller, lighter person will generally feel "lighter" than one from a more massive fighter.
4.3.7 - Red weapons must weigh at least 24 ounces and balance above the top of the hand-grip.
One other rule to consider is that at least 1/3rd of the weapon must be padded, or no more than 30 inches unpadded, and this includes the striking surface and courtesy padding.
4.1.11.7 - No swung weapon may have more than 1/3 of its overall length unpadded, nor have more than 30 total inches unpadded.
Konradr