it's not only the weight (although it's impossible to know because we don't know from what material it is made), it's the distribution of it, it's kind of long.
Which is why big swords are carried on the back, and not the hip.
So if it's being carried on her hip, then it can be reasonably inferred that it's not a particularly heavy sword. The 4 pounds I mentioned earlier is for the heaviest of 1-handed longswords. Most of them sit between 2.5 to 3 pounds, so the distribution is even less of an issue. The majority of weight in a sword is in the pommel and hilt. The blade itself is very light, being a thin and sharpened strip of metal.
Walking and carrying any kind of sword is easy so long as you aren't pathetically weak and can carry 6 pounds without cutting your legs off. The only reason big 2-handed swords are clunky is because swinging it around in a fight is dangerous and unwieldy when the blade is 3.5 to 4 feet long (which is an issue of length, not weight). A 1-handed longsword doesn't have this problem, because it's designed to be used with 1 hand. It's both lighter and shorter.
Unless you're a Final Fantasy character and your sword is 12 feet long and looks like it weighs 25 pounds, and it's held in one hand.