That isn't to say it can't be done, there are a number of ways to alter the crystal structure to prevent the formation of large crystals, or produce a crystal structure that itself has better properties. Generally though that is far more complicated for us to do, but it might not be so complicated to do in a fantasy world with magical materials. Which is why it annoys me, but probably shouldn't.
The really good Frankish and Norse smiths could do it.. Even with their limited equipment.
The biggest problem is temperature control and the correct sequence/method of quenching while not introducing/leeching too much carbon out of any steel ( for a given value of steel... **) that you work with.
A lot of the "fake Ulfberth"s were made in that fashion, resulting in the typical crystal pattern cross sections of those things showing the differential hardening of the outer "shell" and the inner "core".
Which also explains why they shattered the way they did as in tales and archeological finds. They could hold an edge, flex
some, but mistreat them and the right blow....
But honestly, most Frankish swords were made from precasts, then form-forged and ground to an edge. They needed too many of them to equip their soldiers for empire maintenance/the Bashing of the Moors and their incessant internal feuds.
It was generally only the swords of the high nobility that were fully forged ( and often sent as gifts...). Too expensive and too labour intensive to do at scale.
** I have acquaintance of two smiths who actively try to recreate those ancient irons/steels, as they simply cannot be made anymore. Too pure base materials, and modern furnaces cannot introduce all the pollutants..
It's pure Irony that you need very good smiths to make metal that bad in this day and age...