Kouma - (can't catch the first word)... Fall for eternity!
Nanaya - Equipment for an immortal* ... revenge/vengance without bounds!
Nero - Fantastic*, your internal organs. (in better English, "Your internal organs are amazing")
Arc - I'm going dish out/take out/show you* some of my true feelings.
Ciel - (normal) It's because I can't make allowances you know.
- (Shiki) Even if it's Tohno-kun, I can't make any allowances.
Warc - Know my power!
Hisui - "Saturday Night Feveeer!!!"
, or "Haaah, ya!" or "Dark Hisui style... Ancient Hisui Wave Power!"*
Kohaku - "I'll do some cooking and slice you up!" and I can't catch the other one.
*Nanaya - this may be incorrect, I couldn't find the word (hassen) in my JE dictionary, but in the JJ one it listed a legend from China about an immortal, both referenced as hassan.
*Nero - I can't quite catch the first word, could be anything from Spill to I'll have. I keep hearing 'sugoi', for some reason, so thats what I wrote.
*Arc - the words she uses is "honki wo dasu", meaning to show you're true feelings or get serious.
*Hisui - She has three different things she says. The last part of the last one she says "kohou Hisui shouha!", which I couldn't get very clear translations for, but I think it's accurate. Or it could be completely off.
These are not to be taken as accurate in any way, shape or form. The only ones I'm perfectly sure of are Arc, Ciel and Warc. Oh, and Hisui's Saturday Night Fever.