If Salem doesn’t do it for you, that’s totally fair. But I will argue that her primary powers (Immortality, Magic, Grimmcraft) all tie into a very important theme that several of the Magicians of Remnant interact with:
As a general rule, all fighters on Remnant rely upon a combination of three factors to define their personal combat style: Dust, Semblance, Weapon. Ruby has Petal Burst and Crescent Rose. Weiss has Myrtenaster, her Glyphs, and her Dust. Blake has Gambol Shroud and Shadow, while Yang has Ember Celica, her explosives, and Burn. These factors allow each fighter to define themselves in a unique manner, and when operating in combination with one another, create elaborate, intense, and extremely powerful combat sequences. It’s not for nothing that Team RWBY, fully prepared and coordinated, was able to stalemate Cinder in a direct fight.
But this form of Identity Through Combat is optional for the Magicians of Remnant. Ozpin and Oscar never seem to use their Semblances, relying firmly on Long Memory (an overtly magical artifact) and Ozma’s magic. Once Cinder fully attunes to her abilities as the Fall Maiden, she completely discards her Dust clothing and her bow-swords in favor of various forms of Pyromancy. And then there is Salem, and she’s the heart of this point.
Nothing Salem does or accomplishes, she does with powers she has earned. Her magic is inborn. Her immortality is a curse. Her link to the Grimm is the consequence of her attempt at suicide in the Pool of the Brother God of Darkness. None of her powers are earned or really unique, and that’s the point. Magic can lead to stagnation, and a loss of identity.
Contrast these three (two antagonists, and Oscar/Ozpin, for whom loss of identity is a major theme) with the three other Magicians we see: Raven, Penny, Winter, and Maria. While they do develop magical abilities, none of them ever forget their core abilities in terms of Weaponry, Dust, and Semblances. Raven expertly augments her abilities as the Spring Maiden with her usage of Omen in her fight with Cinder, and frequently defers to Omen in combat. Penny only really uses her Magic to either power herself up (via lightning magic) or to supplement her control of Floating Array. Winter, while she develops the power late, does rely upon it in her fight with Cinder, but also relies upon her Sword to engage in close quarters, and her Summoning Glyphs to fight at longer range.
Maria pretty effortlessly articulates this theme to Ruby in Argus: the magic that they both share, the Silver Eyes, is a potent tool, but it is not a tool they should blindly rely upon. Maria actually credits her capability as the Grimm Reaper to her Preflexes, and we’re shown her accomplishment with her weapons Life and Death. Indeed, while her Silver Eyes are useless in her fight with Tock, and it’s her Semblance and her knowledge of her weapon that carries the day. Indeed, this point is hammered home in the climax of Volume 6: Ruby faces down the Leviathan and successfully and consciously harnesses her Silver Eyes… and still nearly dies. It takes the arrival of Cordovin (whom Ruby had shamed for abandoning Argus in a fit of pride) to put the Leviathan down.
This shows a pretty clear thematic line: overuse of Magic can lead to you losing what makes you special (Cinder, Salem, Ozpin/Oscar) and losing yourself.
So that Magic is the gift of the god of Destruction… probably says something.
