Grammar and Terminology
When writing is it better to go for "period correct" terminology or terms that are easier to understand for a 21st century reader. I've always felt that clarity should be more important, and as long as you're consistent with your usage all is well. For example, you don't fire arrows but it scans clunkily when using phrases such as "loose arrows" or "release arrows". This mostly came up when I was working on Hero's Journey. I did do some research to find appropriate terms for things. Sometimes, this resulted in a few surprises. Such as the term "concussion" being used by the ancient Greeks to describe head injuries.
For dialogue, I've always felt that writing grammar should always take a back seat in regards to the way a person speaks. I'm not saying that you should ignore it, but if a character would naturally use a grammatically incorrect phrase, then it should be included in the dialogue. Lord knows I mangle grammar in a way that would even make a Joss Whedon highschool character wince.
What do you thing?