They most likely changed the costume because it is offensive to North America's indigenous population.
In this
article, some Native Americans give their perspective on appropriation of their culture (
emphasis mine)
From what I understand about this game, these are not characters; they are character classes that the player can change at-will. That means you can change from being a "Tomahawk" to being a pirate or a knight. Native Americans' culture shouldn't be used as a costume for aesthetic purposes in a video game. If a game wants to create a Native American character, they should thoughtfully and respectfully give that character background and understand the culture they're borrowing from.
It's sad that we'll complain about the removal of a Native American
costume while we're perfectly content remaining blissfully ignorant of many of the issues facing Native Americans and their nations today. States are still stealing land! I read an article that said one tribe in the Southern United States was asking the state for help to slow/stop the erosion of their land due to a bog that was sinking it. The state just ignored it because all the land that was swallowed by the bog became land of the state.
Native Americans are one of the most likely groups to end up in foster care, and they have very high alcoholism rates. Native women are often abused by men from outside the tribes and have trouble getting justice from the US criminal justice system. In Canada there's a highway where large amounts of Native women go missing, and the Canadian government has done little about it.
We only want to think about them when we can use their culture to make an enjoyable movie, book, or video game, but we can't be bothered to care when their people are facing real problems. I don't blame them for finding that offensive.
I hate all this talk of "giving in" to "Social Justice Warriors." Almost every time I hear that (or read it), it's someone complaining about an issue that negatively affects real communities. Sorry you (not you specifically - I'm speaking generally) thought this costume looked cool and you wanted to use it, but if the only time you're upset about issues concerning Native Americans is when there's been a change in a video game you want to play, you need to rethink your outlook on life.