I wonder if I am missing something or failing to understand the rules. Please, can someone explain to me: When and why should someone use disarming and grappling in a melee fight? Or why not at every opportunity? It does not 'feel' like a consistent combat rule system. I am asking as DM, but I try to keep the players side in mind, too.
First of all, I ask on the assumption that both fighting options are generally available for NPCs and monsters alike (of course, it individually depends on intelligence and body).
Here's the disarming rule from the DMG (p271), which will be the main focus of my questions:
A creature can use a weapon attack to knock a weapon or another item from a target's grasp. The attacker
makes an attack roll contested by the target's Str (Athletics) check or Dex (Acrobatics) check.
If the attacker wins the contest, the attack causes no damage or other ill effect, but the defender drops
the item. (…)
Note: As I read it, the attacker can try to disarm for each of his own weapon attacks, so a fighter on 5th level can do this twice per round, correct?
In some fights (well, in most fights) the adventurers choose their weapons by their effectivity; large weapons with a lot of potential damage or weapons with a damage type or magic that the opponent (in the following, this term refers to NPCs and monsters) is not immune/resistant against.
So, any (at least minimum intelligent) opponent enduring (or fearing) severe damage by such weapons should try to disarm the wielder of that weapon. If that is successful, the effective (!) challenge rating of this encounter may rise – all of a sudden: Think of a vampire that successfully disencumbered the adventurers of all their magic weapons. Or a flesh golem … This strategy would give the opponents quite an advantage.
On the other hand, if I (as DM) start to disarm the characters regularly (or try to), they will pick up the idea pretty soon. Most opponents don't carry an arsenal and many don't have special acrobatic or athletic skills and, therefore, the disarming attempt is quite likely successful (and I strongly dismiss the idea of having to keep the inventory of each opponent up to date) . In the end, most opponents will be far more easily conquered if without appropriate weapons. So, in the end, the game balance would swing to the other side; the players will have the advantage, and because of that, I fear to integrate this disarming option into my games, although of course, players ask for this now and then.
Any attacker with a decent attack bonus can hope to disarm its opponent. (And in situations when damage immunity or resistance is important, it's well worth trying several times to disarm the fatal weapon.) If it succeeds the weapon should be kicked away (free action) so that the disarmed opponent can't take it up again with a free action in its turn without running to it (maybe it is better for the attacker to 'place' the weapon on his own tile (AKA 'step upon it'), in order to 'guard' the weapon? But otherwise kicking away may offer an attack of opportunity …) Of course, the opponent might have more weapons on him, but in most cases those will be of lesser use / inflict lesser damage and so on.
I don't want to make disarming more difficult, but how can I prevent disarming to become the main strategy, in particular for the players? And I don't think they would have solely humanitarian reason for doing so.
As with grappling, its mechanic seems very similar to me in general, but the question is reversed: Why should someone grapple someone else?
Some differences are:
- It requires a dice contest: Str(Athletics) vs. Str(Athletics) or Dex(Acrobatics) – that looks like the average chance of success is about the same as with disarming.
- Escaping the grapple requires an action (opposed to a free action to pick up or draw a new weapon) – that's a real disadvantage, but …
- … since being grappled doesn't prevent a creature to attack, this is really an advantage compared to being disarmed.
Unless one of the effects of having the opponent grappled (opponent has speed 0 and is dragable) is important to the attacker, grappling seems to be useless. Although I admit that the ability to drag the victim CAN be very important, grappling is not a requirement to shove an opponent over the edge of a cliff (PHB p198, 'Shoving a Creature', and DMG p272, 'Shove Aside'). Pushing an opponent to the ground (making it prone) doesn't require to grapple it neither (see again 'Shoving a Creature').
Grappling would make more sense if fighting with weapons (except small weapons like daggers, knuckles) while being grappled would gain disadvantage at least, but that I cannot find in the rules.
Here the circle closes: I would think, that an disarmed (or unarmed) opponent faces an armed attacker, it will try to grapple the attacker in order to get into a close-combat situation (wrestling, fist fighting, …) where weapons can't help much – or to flee completely.
Best Answer
How can I prevent disarming to become the main strategy, in particular for the players?
You probably don't need to. If you look at a typical adventure, most of the dangerous enemies do not depend on weapons in the first place, so disarming them isn't even an option. You can't disarm a wolf, a black pudding, a dragon or a demilich. Even in cases where disarming may hamper the opponent, you have to consider that this means up giving an attack. Which means giving up damage. Which means delaying the opponents demise. And being dead is far more crippling to most creatures than being disarmed, especially considering most enemies that do use weapons carry more than one, and even if they didn't there are still things they can do without weapons... like trying to get their weapons back. Merely kicking the weapon away a couple of feet isn't going to seriously hamper them, at best you'll maybe get an extra attack of opportunity out of them. Other weapons being "weaker" also rarely matters, since for most weapon wielding creatures the majority of the damage comes from bonuses, not the weapon damage die, especially for stronger enemies.
Why should someone grapple someone else?
In a one-on-one fight there's little reason to, as you've outlined already. But that's not a typical situation in D&D. The main reason you'd grapple someone is to keep enemies in place to keep them from reaching objectives, avoiding harm, or most commonly to prevent them from charging past the frontline and munch on the squishy wizard of the group. It not giving any disadvantages to the attacker other than not being able to move isn't really an issue, because typically the one doing the grappling would be a character that can afford to take some hits, because they have high AC, high HP or both. In fact, grappling comes up far more often during fights than disarming, contrary to what you seem to believe, because unlike disarming it does actually work on most creatures.
A character with an especially great strength advantage over their opponent can make even more use of this by also shoving their opponent prone – meaning they'll have disadvantage on melee attacks, melee attackers having advantage against them, and until the grapple is broken they can't stand up either. And of course even if they do break the grapple and stand back up, this uses their action and half their movement for the turn so they can't really effectively fight back or run away once they're in this situation.
TL;DR: You're overestimating how useful disarming an opponent is, by a lot, by failing to take into consideration how many opponents will be unfazed by a disarming attempt. You're underestimating how useful grappling an opponent is, by a lot, by failing to take into consideration how many options the grappled victim loses if they weren't planning on melee attacking the grappler already. I think you may have a skewed perspective because you're imagining a lone low level character fighting a lone low level humanoid enemy; In that situation the relative value of disarming and grappling and such may be different but that's not something you typically see in D&D.