Hey there Jake. My name’s Stefan, and I’ve been around this game a couple of years. I’ll be happy to answer any questions you’ve got, just reply to this message.
As far as Assassinates and Backstabs go, you’d need to say it in a voice loud enough to have its target be able to hear the ability. With most abilities you don’t need to use a very loud voice–just a normal one. In addition some things can be counted or said in a whisper, like channeling and aiming. This whisper must be somewhat audible though as it basically indicates to those very close to you that there is a fireball forming in your hand or a bow being deftly slung.
Some abilities CANNOT be done stealthily. One example would be killing blows. These are attacks used on a helpless and dying victim to make them completely unconscious and speed up their death count from first(crawling, can whisper) to critical(can do nothing, is a body on the ground bleeding out). Killing blows must be counted slowly and loudly so that everyone who sees you doing it can hear it, and know what is going on.
Finally, some Erudite (top level) abilities can instantly down and killing blow a character without the need of a count. An example would be Master Assassinate. Super dooper Assassin’s Creed style.
Reply to me with any questions, and I hope to see you in game!
Ah-has Opes, current title-holder of "Greatest Archer in Midworld."