The artefacts he purchases from players are relics from the God Wars. Players cannot exchange the artefacts in noted form. In addition, Mandrith and Nastroth will not buy weapons or armour received as drops, as he advises the players to use them, rather than trade them for money.
This towering figure is descended from the first of the clans of men, whose legends speak of the first murder on RuneScape. For this crime, his people have been cursed to an eternity watching over those who would do the same. Given his terrifying dress, the massive blade he wields and his remarkable size, it is little wonder that he survived in the Wilderness. According to Mandrith his robes have been passed from father to son for generations. He appears to be equipped and skilled much like a player killer in old-style Wilderness: a fast and deadly weapon, with little armour, wild-looking and very strong without much dexterity abilities.
Mandrith used to be the custodian of the Wilderness Volcano when Bounty Hunter was hosted there (bullying his banker, Maximillian Sackville) constantly, but had to close it due to a particularly violent eruption. When various monsters moved into the crater Mandrith abandoned the volcano and moved to Edgeville.
According to Sanchez, when Mandrith was in the Wilderness, he hired Scotty and Sanchez to clean up for him, paying them 76k coins per hour.
After Ritual of the Mahjarrat, talking to him about the Dragonkin's attack on Edgeville will show that Mandrith helped people get to safety, and saw a myth. Upon the player telling them that they are dragonkin, he tells the player to not say their name again or they will come back. This suggests that his people greatly fear the dragonkin.
His examine text used to be: "The custodian of bounty hunting and PvP worlds!"
If you give him a weapon, armour or anything not related to an artefact, he will say "I don't know what to do with that."
If you give him a noted artefact, he will say "If you brought me the actual item, and not just a picture of it, I could give you some money for it."
His dialogue where he explains he pays the duo 76k an hour is reference to players using the tactic of 76king, a method of taking advantage of the PvP system to get large amount of coins with little effort.
Mandrith has a crippling fear of skeletons, a weakness he keeps hidden.