Put anything on your arm you want. It's not as if some dude is going to walk up to you with a grin on his face and laughingly ask you, "dude, do you know what that means?"
Etiamsi sit in tenebris anima mea, oritur in perfecta luce; astra amavi nimium metuenda noctis.
There are words that don't reflect in Latin - "set" for example. Latin has no punctuation. Also it is easier to get a good translation if you break it into three clauses. That's a loooooong tatoo.