Complex sentence: Craig Hogg has suggested that the watcher in the water may be a guardian of Moria who attacked anything evil so sensing the ring upon Frodo the watcher only attacked him thinking that he was also evil.
Split into simpler sentences: Craig Hogg has suggested that the watcher in the water may be a guardian of Moria who attacked anything evil so sensing the ring upon Frodo. The watcher only attacked him thinking that he was also evil.