Texture Pack Not Working?

You mean transparent outline in the item? Open texture in any graphic editing program that support transparency, paint.net for example, then Ctrl+A the whole thing, Ctrl+C, add new layer, then paste by Ctrl+V, merge layers, after that repeat - it will make edges of the item full-opaque

Alternatively you can use 'magic wand' tool in the tools menu on the left and select transparent area around the item texture, then go to 'Edit' tab and 'Inverse-selection', now add new layer(it must be under our main layer) and select black color - after that press Backspace button to fill the selection, after that merge layers and save the file.

I don't know if you can fix it, but if it's possible, then it would be in the item model.