While I expect Dark Petition to be more of a maindeck card, it is worth keeping in mind as a sideboard option for decks that want an extra copy of a few cards they can only play one of in the sideboard
In terms of abilities, beyond simply being a Knight himself, Oakenshield also lets you recur one creature a turn from your graveyard to your hand, giving you the staying power you need in a long Commander game
Poor bulk storage can cause corner dings, surface scratches, and warping, which can lower resale and grading value
Once per turn, if you control no other monsters: You can Special Summon 1 "Noble Knight" monster from your Deck in Defense Position, except "Noble Knight Medraut", and if you do, destroy 1 Equip Spell you control
In addition, 15 cards can be found as Collectors Rares, and several as Quarter Century Secret Rares
Prism Ring, Liliana Heretical Healer, and even Blood-Knight give us a lot of new options to consider, which then changes the power of the many great black cards that require payment of life