Visually, I like each race to have distinctive styles. There isn't really any mechanical effect, though it can have a role playing effect. A human carrying an orc sword sends a very different message then one carrying an elven blade. At the end of the day, it still does 1d8 points of damage, but it's how it says it that can often times be important.
The most distinctive and expressive weapons tend to be blades, from spears to daggers to two handed swords, a blade can say a lot about a society.
Human blades tend to be leaf shaped, flaring out from a narrower base. The length of the blade tends to impact the width of the widest point. Longer blades tend to have a more subtle shape than shorter blades. Specific decorations, materials, and styles will vary be region, and even by smithy, but they generally follow the same basic pattern.
Dwarven smiths tend to make fewer swords larger than a short sword, mostly owing to the traditional preference towards axes and hammers. Yet Dwarven sword smithing is still a highly refined art. Their blades tend to be straight, and while the short sword is the most common, examples of both long and 2 handed can be found.
Elven blades are light and elegant. Single edged curved blades with a slightly re-curved grip are the norm.
**Pictures stolen shamelessly from all over the internet.