Chainmail, OD&D, and Magic Swords
One of the classic tropes of D&D, for good or ill, is the magic sword. A sword that is just magically better at doing its job of hurting and killing people. Maybe it has a few other properties like glowing blue in the presence of orcs or evaluating the "alignment" of the person holding it. But at the most basic level, it's a +1 sword. When you make an attack roll, you add an extra +1 to the D20 on top of whatever you would add from your class or ability scores, and you add an extra +1 to your damage roll. However, in OD&D, the latter was not the case and magic weapons only improved your chance to hit.
Unsurprisingly, this is not incredibly impactful. You're increasing your chance to hit by 5% and your damage by about 20%. However, players mostly care about their hit-chance as that's what they get immediate feedback on. Additionally, the damage boost is not as impressive as it might seem once you realize its goal, reducing the enemy's HP to zero. Against an enemy with 1 hit-die (HP rolled randomly), the chance for a single sword-stroke to slay them only increases by ~10% when you add +1 to your damage roll. This conflicts with the supposed idea of magic swords as presented by both Chainmail and OD&D. Each one was supposed to be a rare thing with its own personality and name. That's a level of importance that doesn't seem fitting of such a slight increase in fighting ability. However, this makes more sense when you realize that OD&D was initially supposed to use Chainmail's combat resolution system.