At some point in time Nalphtum discovered the existance of a secret society that was led by the Fiend Dozzu which included his wife, daughter and Nashetania's uncle which would be either his brother or brother-in-law, and he attempted to fight back against them in way that came accross as paranoia to many, as his decision to place a bounty on members heads without due process led to many nobles using this law against commoners out of pettiness and commoners "ratting" out nobles to try and leach their status for themselves. His own Daughter amongst those he accused he tried to have her executed and adopted a distant relative of another country to be his heir instead. Eventually he was stripped of his ruling status in all but name only, and is now a figurehead with Dozzu's faction seemingly being in control of the nation.
It is also presumed that he was the one who gave Goldolf Aurora the secret Sacred Instrument: the Helmet of Truth which had been passed down through the royal family.
Nalphtum is remembered a paranoid and irrational leader who was deeply afraid of a cult of worshippers of the Evil God being after his life and that of his country, even accusing his own daughter of being a member (which she in fact was) and it was eventually dicided that he would be stripped of his powers as monarch and lead the country of Piena in Name only - a Prime Minister being the actual person making the king's decisions instead.
Given the revelation that one such secret society does in fact exist and that Nashetania was indeed a part of it it could be construed that Nalphtum was far more insightful and intelligent than was widely believed, but he was nethertheless irrational enough to place a bounty on the heads of supposed members of Dozzu's faction (possibly a political move to try and put pressure on them to slip up more than anything else) which led to many a people divided and busing this law for self benefit and many innocents suffering. A possibility for this irrationality was knowledge that his own family members were in fact members of this sect.
At present he is at the very least capable of basic interactions and a a public image when needed.