Complex sentence: MEDUSA is also the name of a fictional energy weapon in Philip Reeve's novel "Mortal Engines" although it is completely different to the real-life weapon and is not known to be an acronym.
Split into simpler sentences: MEDUSA is also the name of a fictional energy weapon in Philip Reeve's novel "Mortal Engines". It should be noted that this MEDUSA is "completely different" to the real-life weapon, and is not known to be an acronym.