I found that in the case of 'Brave' the name Merida was chosen because the look is easy but similar to Mairead, a Scottish Gaelic name, the form of Margaret. Plus, both Merida and Mairead are similar to the English word /married/ because marriage is an important issue in the plot.
I think this would be a pretty name. It sounds like a prettier version of Meredith or Mercedes. I have no idea how this name is pronounced in the movie, but I would pronounce it like the Spanish city.
"I...am...Merida! And I'll be shootin' for my own hand." -Merida~BraveHonestly, Brave is my third favorite Disney movie. I wouldn't use this as a name for my daughter, I don't care for it.