While I went into great detail about the entire system of effects in the Impact Effects post, I just wanted to quickly share the sprites I made for the Sword Swing and Sword Slash effects so you can see exactly what's playing out when you watch our characters attack each other. It took a good amount of iteration on these to get the effect I wanted and the great feedback I got from people I showed it to was instrumental. Anyway, the sprite for the sword swing effect looks like this:
What really helped me create this animation was using a perfect circle as a guide. When I was producing this sprite I kept circles in the image to act as guidelines:
There's a slightly different effect that plays out whenever a character swings a shield. I altered it slightly to more resemble a shield by rounding it out a bit and by giving it a milky white center for a little bit of weight.
The slashing effect took a lot of experimentation to look both correct and distinct. It started out fairly unremarkable but became interesting as I continued to iterate on it. Notice the preliminary "burst" that occurs in the first 5 frames before the slash even begins. It's barely noticeable, but it creates a subtle sense of impact. The sprite looks like this:
In this piece of interactive Unity content, you can push 1 to watch the sword swing sprite play out, 2 for the shield swing sprite, and 3 for the slash effect.