Names (and surnames)

[Trexller]

in keeping with game lore and plastic not existing in norrath (until dwarves discover oil) the opposite of leaf would be stone or metal - Darksteel, Darkmetal

dwarves being mammalian would bleed red

Brellsbane it is

fits the character's persona, rolls off the tongue with nice alliteration

it's basically dwarfslayer, but without being a super common concept

Brightleaf Brellsbane

maybe too much B's

Brellslayer, Dwarfbane