I have seen many videos on Youtube where there are many cool animated texture packs that are just the sandstone blocks so animated that they change the color scheme because I found that very cool I downloaded such a texture pack but the blocks are not animated or they do not change the gradient please contact me
You go to the .minecraft folder and go to resourcepacks. Here you can choose the pack where you want to change the textures - Open it for example with Winrar or 7zip and go in assets and to find the sword, in textures and items. Here you draw the item, what you want to animate on your desktop and have to edit it now. I can recommend you the program Paint.NET!