The tutorial (https://fabricmc.net/wiki/tutorial:shield) has the blocking model parent from fabric_banner_shield_blocking and doesn't specify the texture.

However, specifying the texture like so in the blocking model (my JSON) results in the shield using the default Minecraft missing texture.

  "textures":{
    "shield":"botaniacombat:entity/elementium_banner_shield"
  }

D'oh, I had it parented to fabricshieldlib:item/fabric_shield_blocking instead of fabricshieldlib:item/fabric_banner_shield_blocking, which is why it didn't work. My apologies, and thanks for your patience, haha.

It's all good! Happy you got it sorted out.

thats not what happens on my end, could you please show your project, preferably as a github repo?

Thanks for catching this! It seems I changed it in the code but not in the wiki, will fix in a sec!

fixed

Thanks for the quick response, but there still seems to be an issue.
using
"textures":{ "shield":"examplemod:item/netherite_shield" }
(which is what the wiki has now) in the blocking model uses the non-banner-compatible shield texture. It looks like the banner disappears when blocking.