The equipment of YGGDRASIL was normally installed using an external crystal drive, so it was hard to standardize the looks of equipment. But since a lot of players hated wearing mixed pieces of equipment, it was resolved in one of the version updates.
It added the option to standardize the appearance of equipment without affecting its stats.
The black armor that covered Ainz’s whole body had several requirements and possessing the ability [High-Level Item Creation] was one of them.
Right now, Ainz was equipped with [Sure Hit Glasses], [Crown of mental Barriers], [Clothes of the Black Widow], [Black Belt], [Metallic Gauntlets], [Nemean Lion] and [Boots of Speed].