Good start! I think you can get an immediate improvement if you change the blending mode of the symbols to Multiply. That will eliminate the little white bits at the edges.
Multiply works by darkening the background according to the darkness of the foreground. If a foreground pixel is completely black, the resulting blended pixel will also be black. If the foreground pixel is white, the blended pixel will be the same color as the background. Shades of gray in the foreground will darken the blended pixel by an amount equivalent to the luminance of the foreground pixels. You can also adjust the opacity/transparency of the foreground layers to tune the blending further.
I'd suggest you also experiment with blurring the symbols slightly. Right now, they are very sharp, but your parchment background is blurry. The difference is large enough that I doubt you'll be able to really match them, but you can certainly get them closer.
Welcome to the guild, and enjoy your time here!