While some items are server-side and tied to your Ubisoft account, editing can help you access various weapon attachments and mission progress. A Note on Safety and Fair Play Anti-Cheat:
Jump straight to Level 30 or adjust your Tier One ranking. Popular Tools for PC Save Editing
Once a save editor is found, follow the provided instructions for download and installation. Be cautious and ensure that the source is safe to avoid any malware.