We don't have synonyms for long sword yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are longsword, long-sword and longword.
(n) :
Alternative spelling of longsword. [Any type of sword that is comparatively long; depending on context, applied to swords of the Bronze Age, Migration period, Viking Age and Renaissance era.]
(n) :
Alternative spelling of longsword. [Any type of sword that is comparatively long; depending on context, applied to swords of the Bronze Age, Migration period, Viking Age and Renaissance era.]