I have several documents that require my signature and an image of my professional seal. I need to protect my signature and seal while still allowing the document to be edited by another party. The other party would need to add their signature electronically. Protecting the entire document would require the other party to have the password - which defeats the purpose of protecting the document.
If this a picture of your signature and seal, then forget any idea of protecting it, completely. If it is on screen it can be copied and used to make another document in seconds. I will not say how, but it requires no specialist knowledge.