|Image from Dark Classics
Jack recently wrote about differentiating weapons. I have also in the past sought to make weapon differences meaningful over and above damage dice, with varying levels of success. Jack’s proposal has some Third Edition assumptions (such as critical ranges) that I don’t use, but I find one of the properties he gave daggers particularly interesting. In his system, dagger wielders may use movement actions to attack. Presumably, this is to represent quick close attacks and perhaps grappling.
I am, in general, not enamored of the action economy approach to combat. It tends to slow play down and make the decision process more complex without adding corresponding depth. For more on how this worked in 4E, and the proposed simplification for 5E, check out this blog post. Fifth Edition is also experimenting with other ways to spend combat time resources which look intriguing, such as spell concentration being required to maintain continuous effects (which should help control the problem of appropriately enchanted wizards being potentially better at any conceivable task, a problem that I gather can be relatively acute in Third Edition and Pathfinder, though I have never played high level games in either of those systems). For more on concentration in 5E, check out the second half of this Legends & Lore article.
What kind of OD&D implementation based on movement might work for the dagger? Before a dagger wielder can get any kind of benefit from close fighting, they must first get inside an enemy’s guard. It seems reasonable to model that as a successful to-hit roll. They must also successfully bypass any kind of “hold at bay” active from pole-arms. Once the dagger has hit, the attacker is considered up in it and future attacks do “two dice, take highest” damage. Note that this also applies post-backstab for thieves. As long as the attacker chooses to maintain this disposition, no significant movement is possible, as they are focusing on carving up the target.
This is similar to a grapple (though there is no grabbing going on). Pole weapons are almost impossible to bring to bear against a dagger wielder up close, and all weapons other than a dagger or short sword attack at -1. The target may disengage by spending an action and making a successful dexterity check. Fighters may attempt a disengage maneuver along with a standard attack, but all other classes must spend all their efforts just to get the sharp thing away from them. Whether or not dagger work can be used effectively against non-humanoid enemies should be determined situationally (bear: sure, purple worm: not so much).