Like, it's a fake weapon, badly designed, intended to look cool. But in universe, what's the history?
There's multiple ways to give a canon reason a badly designed weapon is such a cultural icon. Maybe it's based on the horns of a predator, or something like that, as an example.
I'm not a deep delver into such things, but I wonder if there's an official history behind it.
Like you guessed it is a cultural icon. The emperor that united their home world used it.
In Star Trek lore, the Klingon Kahless created the bat'leth around CE 625. According to Klingon mythology, he formed the blade by dropping a length of his hair into some lava from inside the Kri'stak Volcano, then cooling, shaping, and hardening it in the lake of Lursor.[5] He then united Qo'noS, the Klingon homeworld, by killing a tyrant named Molor with the weapon, which became known as the Sword of Kahless.
See, that makes sense why it's a less than ideal design. We have weird weapons here on earth that have significance, but aren't ideal designs. The batleth is more of a hungamunga than a longsword :)