{solved}

You cannot change the base damage of a weapon.

You can use the Attunement box to add the Dragonborn only requirement but it will not be enforced by the system, it will just be text. Ensure you check Requires Attunement box.

The features you describe cannot be implemented by the system so they would just be text in the description.

You cannot delete the others because you published them (shared them publicly). There was a big popup telling you that once shared you cannot delete them. This is why you should read the popups. You shouldn't share anything until you have done all testing and editing you wanted - you don't need to share it to test it, use it or have other people in the same campaign as you use it. 

Quote from Cyb3rM1nd_Test >>

You cannot change the base damage of a weapon.

You can use the Attunement box to add the Dragonborn only requirement but it will not be enforced by the system, it will just be text. Ensure you check Requires Attunement box.

The features you describe cannot be implemented by the system so they would just be text in the description.

You cannot delete the others because you published them (shared them publicly). There was a big popup telling you that once shared you cannot delete them. This is why you should read the popups. You shouldn't share anything until you have done all testing and editing you wanted - you don't need to share it to test it, use it or have other people in the same campaign as you use it. 

 
Not only is all of that information 👆completely accurate, it is all readily available in the Items & Equipment section of the Homebrewers’ “How To” FAQ: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/131411-a-homebrewers-how-to-faq#HomebrewItems&EquipmentFAQ, a helpful resource for almost every homebrew project done on DDB.