From the sound of what Dave was telling us about Fenris' combat dialogue, I'm kind of reminded of Thane from ME2. Fenris is technically a living weapon, so to him combat might be like a meditative state, where Fenris just lets go and lets his conditioning take hold until the end of the fight.
On the subject of Tevinter-Speak
Fenris: Hawke. I, well Ei vento nai mordoi deid.
Hawke: Well that's good to know sweetheart, but I hope that's not something you decided just this minute.
Fenris: Wait, you speak Arcanum?
Hawke: I know a few things, especially what you say about me in your sleep.
Fenris: (muttering) Fenedhis.
(First little blurb translates into "I don't want to kill you" from Arcanum)
On the subject of Fenris' sword:Isabela: That is a fine blade Fenris. What do you call it?
Fenris: I call it a sword, it is a weapon.
Isabela: I know that Fenris, but most warriors have names for their weapons. Varric's crossbow is named Bianca, and this dagger of mine is named Ezra.
Fenris: You named your weapon after Hawke?
Isabela: (smiling) He gave me this dagger, and just like its namesake it protects me and is always by my side. He carries one named after me. That's the idea behind naming a weapon, it conveys the owner's personallity.
Fenris: This blade is an extention of my arm. A tool. Nothing more.
Isabela: Well then, perhaps you'll change your mind.
Fenris: Perhaps I shall name this blade Silence. as a blow from it stops my foe from bothering me about trivial topics such as the name of my weapon.
Isabela: Touchy today aren't we?