The Realm of Shadows may be the same World of Shadows as the one that becomes visible when a [Elixir of Shadows] is consumed. It may also have something to do with shadow magic and shades. Death knights, necromancers, and undead as a whole share a strong connection with the Realm of Shadows from many hints that can be seen in-game. In the death knight starting zone, death knights are given the task to enter the Realm of Shadows in order to gain their Deathcharger. Later on, death knights are eventually able to learn the ability [Raise Ally] which pulls their ally's spirit back from the Realm of the Dead and forces it back into their body. Upon doing so, a buff is applied to the player stating that: "A touch of the spirit realm still lingers..." This shows that death knights and necromancers both have a connection to the Realm of the Shadows/Dead to perform necromancy which furthers the idea that they actually are drawing their magical power from it.
One thing that has always been remarkable to me in World of Warcraft is how it brings players together from all sides of life to meet with common goals. I've been playing the game for fifteen years, and have played with gamers with all sorts of accessibility needs. I distinctly remember raiding Serpentshrine Cavern back in the day with an amputee friend Paladin who healed an entire raid of 25-players using a mouse equipped with dozens of buttons. He also competed at a high level in World of Warcraft Arena, as well as any able-bodied player I've seen.
Claim a covenant's power: players will be called upon to forge a bond with one of four covenants that rule Shadowlands' new zones, setting the tone for their journey through the expansion with a full covenant campaign. As they level up, they'll get new abilities based on their choice, including class-specific abilities for each Covenant—as well as developing soulbinds with specific covenant members, which grant them access to that character's specific traits and bonuses.
Of course, though, many disabled players have unique challenges that require even more specialized equipment. The open nature of PC makes gaining access to these tools a little easier than it is on a closed platform like a console, but Blizzard is making it easier still with Shadowlands later this year, which is now testing full-blown controller support, complete with the Xbox Adaptive Controller in mind.
Sometimes, the spirits roam the Shadowlands without resting. It can be because their resting place wasn't complete, because of a battle in their resting place or because of the corruption of their resting place. To bring eternal peace to the souls, it is needed to destroy the source of corruption or by making a ceremony with items such as [Tuskarr Ritual Object]. A spirit in the Shadowlands can, with enough power over other souls, tear a hole into the living world once they are strong enough. This is how Jin'do returned to Azeroth.