But you can still miss with a greataxe, or a maul, or a halberd. How come they can miss but the greatsword can't?
Because WOTC implemented by weapon not generally which was originally how 4e did it.
In 4E any fighter could "Graze" with any weapon by choosing the Reaping Strike exploit. Not just 3 weapons. Any melee weapon if you dedicated on of your choices to it.
That's why it's just a sprinkle of 4e instead of fully embracing it.
I'll say it again. Just because I (and obviously others) don't like Graze, or the "Damage on a Miss" mechanic in general, doesn't mean that it is objectively bad. It is a matter of preference. Trying to argue and rationalize "No, really! It makes sense!" Isn't going to help. I understand that you can come up with a reason for it, but it doesn't change the fact I don't like it
I'm not trying to make you like it.
I'm trying to explain it.
D&D lacks a core Perry mechanic, Dodge mechanic, and Block mechanic.
In D&D if a monk punches you in the face,
there is no mechanic to put your arm in front of the fist and block the punch not swinging your arm in the path of the fist to party the punch. Blocking and Parrying are excuses within a amalgamation of all all the mechanics.
I mean your AC doesn't change in melee regardless if armed with a fist, dagger, short sword, longsword, greatsword, or halberd.
Nor is there a feat to do it.
But all shields no matter what size is +2 AC. Oh Caiphon.
I'm not saying you have to like it but D&D simplifies stuff and important stuff disappears into the nebula of narrative. I personally don't stress some details because other details are just as dumb and turns would take forever if we did.
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Oil of Sharpness is just bootleg liquid residuum from. 4e.
Pour goop on swords to make magic swords.