As of the DMG’s launch (DMG p.271), there is an officially suggested competition for disarming attempts. It is utilizing a contest if you are not as educated as the Battlemaster. It certainly seems like the aim of a section like this would be to allow you to attempt special maneuvers (like disarming) as an action in battle. The DM can make use of these contests as versions for others. It is about Grappling and shoving a creature. This section contains the most common competitions that require an action in combat. You may see that the sidebar in the segment on Grappling/Shoving a Creature (Fundamental Rules p.74.) A contest symbolizes such a challenge. That is the closest thing to a general rule for Disarm 5e dnd. It is to assess if it’s larger than the attacking creature or a disadvantage if it’s smaller. The goal has an advantage in its ability. The attacker has a drawback on its attack roll when the goal is holding the item with at least two hands. Suppose the attacker wins the contest, the attack causes no damage or other ill effect. The attacker makes an attack roll contested by the target’s Strength (Athletics) test or Dexterity (Acrobatics) check. A creature in dnd can use a weapon attack to knock out a weapon or another object from a goal’s grasp.
The discretionary principle for disarming (DMG p271) is as follows.
