It's unfortunate that modern Wonder Woman comics and now this film have borrowed so visibly from the Xena:Warrior Princess series, I will never approve of Wonder Woman carrying a sword as a daily accessory as it is a symbol of violence, confrontational, and being superpowerful already she simply doesn't need it.
But as you suggest by adding it to the film version it does distance her from being just another Superman/Supergirl strongwoman. The snag being that if she IS strong enough to stand her ground with a Superman or Doomsday then, once again, a sword is a strange and worryingly violent accessory to be using so visibly and with such familiarity. It makes as much sense as giving Supergirl a sword really - Why should she need it? or want it?
Think could be useful to show her off as being really skilled in fighting, but that she should normally have just her lasso on her...
And the previews make it look like she is channeling lightning or something also?
Does look though that WWI weapons can really her her and the Amazons to a degree..