Unlike the Shield of Samar, the Promethea did not possess the ability to resist sustained enemy attacks, especially once it expended its resonance shield.
Though its transphasic armor system gave it a moderate advantage against opponents that did not possess any transphasic capabilities themselves, it was unfortunate that the Gauge Dynasty happened to be one of the parties that invested a lot into them since its agents first stepped foot into the Red Ocean!
The research and development they allocated to phasewater and its many applications far exceeded that of the Larkinson Clan or any other private organization. As the Gauge Dynasty was as large as a medium-sized state by itself, it had no lack of senior scientists and capable research institutions.