@amyeha I’d start by making a small test with some text. Doesn’t matter what font you use, or what it’s saying, doesn’t even need an alpha, just an image of some text (You can make some text in a new scene, make the camera orthographic and clear it’s rotation and location, by pressing ALT-R and ALT-G, raise the camera a bit on the Z-axis, so that you can see the text through the camera. Remove all lights from the scene and set the strength of the Environment to 0. Give the text an Emission Shader, pure white and render).
Now put that on the sword to see how it looks. (Pixelated?)
If necessary, double the resolution of your Texture. When you first paint your Texture and then try to put on the runes, you might end up having to paint all over…..
