It's hard to say that Amelia really specializes in white magic. She knows a lot of
Shamanism magic as well (in fact,
Ra Tilt is a Shamanism spell). Some of her more powerful white magic spells are
Megiddo Flare, a spell that seals the undead within a
Binding Stone, and
Holy Bless, a spell that destroys the undead (I've only seen her use this in
Slayers Royal for the
PSX).
Amelia's trademarks are her unquenchable thirst for Justice (seigi, in Japanese) and her amazing clumsiness. Amelia runs around telling all of the antagonists that she's going to strike them down with the Hammer of Justice, a purely fictional weapon I assure you. She usually begins a battle by standing on top of a tree (or, for lack of another high spot to stand on, on top of Gourry's shoulders), and unleashing a diatribe about truth, justice, and all kinds of other nonsense. The extent of her passion can be seen in Lina's vision of what Amelia would do with the Dragon Slave.
Man: *sees money on ground* Wow! A coin! *bends over to pick it up*
Amelia: That's stealing! Stealing is wrong! Dragon Slaaaaave!
And Lina is right. That's exactly what Amelia would do.
After Amelia's longwinded justice speech, she attempts to flip down from where she was perched. She lands on her head, or her butt, or some other painful spot. The only spot that she DOESN'T land on is on her feet. Amelia's acrobatic un-sense pays off in one episode where Lina, Gourry, and Amelia are escaping from Zangulus and Vrumugun, and Zangulus tries to jump off a bridge onto their raft. They get scared, but Amelia chimes in and says "There's no way he'll ever land on our raft!" And he doesn't. Instead he lands on a giant eel that attacks the group... But anyway, I digress...
Amelia's specialty spell is Visfarank, a spell in which she channels magical energy into her fists to punch the enemy. In Slayers Royal, this makes her punches about as effective as the sword that Gourry uses (which doesn't look like the Sword of Light in the game, but does a HECK of a lot more damage than Zelgadiss' sword).
Amelia's name is actually supposed to be Ameria, but since Amelia is a real name and the equivalent of Ameria, it was translated to Amelia in the US.