Here are my considerations:
For the Shade, I'd use "Úmbreo". But then again, I presonally translate the Shadowfell as "Penumbra" and the Feywild as "Feéria".
BTW, I translated the reigns as Selvagem Feérico, Desolado Sombrio, Escuro Profundo.
Figher = Guerreiro (works better than Lutador, even though Guerreiro is actually Warrior)
Knight = Cruzado
Rogue = Desgarrado (and Scoundrel = Trapaceiro)
Warpriest = Sacerdote bélico
Ranger = Ranger or Patrulheiro (I keep being reminded of Hank from the D&D cartoon being called "Guarda")
Cavalier = Cavaleiro (I switched this with Knight because the Cavalier can actually get a mount)
Warlock = Warlock
Hexblade = Hexpadachim? Lâmina-Hex? (I like keeping the word "Hex", but then again, I'm a Jonah Hex fan)
I think 'guerreiro' brings to much of a war-like feeling, and not all fighters go to war, a fighter like a slayer is a perfect example. It is kind of a mercenary, it might go to a guerrilla, but not a war. Also, not every 'guerreiro' is a fighter, a mage can go to war (Gandalf anyone?), even a (war)priest goes to war, or a paladin, etc. 'Lutador' brings the idea of someone who fights directly with its hands and weapons.
Rogue as 'desgarrado' is the correct translation, but in the D&D world, rogue is a cunning lone worker with lots of skills (the Thief begins the game with at least 6 of them). In that sense 'Ladino' is also a perfect match as it tells us just that.
About the warpriest, both means the same thing, but when I heard 'bélico' I think of priest with a plate armor walking like a war tank with a sword twice its size on its back, a bit to much...
Ranger is a damn word with no good translation, but i'm used to patrulheiro, if you add to equation that we have Warden in D&D that is a 'Guardião' das florestas.
The Cavalier/Knight debacle. The Cavalier was an specific order of knights (and it wasn't even a holy order), but in the D&D world a Cavalier is someone who goes in some sort of holy cruzade. Now the knight, is the old knight in shinning armor (it has plate in the start of the game), and althought no horse is directly involved, 'Cavaleiro' is the word to use here. I thought about using the world 'Soldado' to mean someone with military training, but 'Cavaleiro' is more correct. In the end both are very similar, but since the Cavalier have vows and holy atmosphere, I think 'Cruzado' is more fitting.
Warlock, I came this far, what is one extra word?
Hexblade, hex would mean to us 'praga' ou 'bruxedo', a hexer is 'rogador de pragas, praguejador, praguento'. I think hex in hexblade means the Hexer, not the hex so I used 'praguejador', blade simply means 'lâmina', but in that sense, 'cortante' ou 'afiado' is more fitting, also 'afiado' means someone with cunning or malice.
Revenant = Revenante
Shade = Úmbreo
Pixie = Pixie
Skald = Skald (we don't translate "viking", so "skald" stays)
Revenant is french, I really would like to give it a portuguese word to it.
Shade means in the shadow or covered in shadows, 'tenebroso' means in the darkness or covered in darkness, almost a perfect match, and 'tenebroso' also carry that grim aspect to the word.
Pixie is a very hard one, I thinking about using 'Fadinha' (little fairy), or maybe 'Fadinha Travessa' (mischievous little fairy). The translation is a bit juvenile, but I can't see a Pixie being used in a game that doesn't have a childlike or comic aspect to it. Actually, I still don't know if a Fairy in D&D is human-sized or small like a pixie. Anyway, did you all know that Fey is a corruption of Fay (from fairy), also, I think I can safely assume that all Fairy references in D&D books can be replaced with Fey ('feérico') as an adjective and work just nicely, this way I can even call Pixie 'Fada'. Do you know of any creature that is specifically refered to as a Fairy (not as "family of creatures" fairy)?
Skald have a direct translation to portuguese, why not use it? Berserker doesn't have one, so I have to stick with the original.
Also, I don't think 'algoz' fits the Slayer, it is vicious and vile, a Slayer is just devastating (btw: I thought about using Devastador, but Matador still won).
Keep up with the feedback, it is helping a lot. I'm begin to translate lots of materials form the Essentials line since it began, I just love to research words and translations. I've spend days in a single word.
PS: I still think about translating halflings to 'pequeninos' (this word that was used in LotRS). If I did that, the only one left would be Tiefling, do Tiefling derive from anything like halfling from half-people.