He loves a good battle — or even a bad one — and owns a magic Sword of Unbeatableness which neatly slices all enemies into two and renders the wielder invincible. Just the deity you need for those late-night role-playing games.
However, his special powers were not enough to save him from having his hand hacked off in battle one day. This cost him the Kingdom of Ireland as no-one wanted a one-handed king. Disability discrimination was widespread in those days. NUADA was forced to turn to his brother DIAN-CECHT for healing sessions and therapy.
Meanwhile the evil BRES had claimed Ireland for himself on the grounds that, although he might be half-demon and a homicidal bastard, at least he had full complement of hands. Poor NUADA had to wait for the TUATHA-DE-DANANN Justice Dept to oust the usurper and restore him to his rightful place. Even then he never received compensation.
On the other hand, his brother did manage to fashion him a lovely shiny new hand made of purest silver.