Haela Brightaxe is a Dwarven goddess, a demipower member of the Morndinsamman ('High Shield-Brothers' -- the Dwarven pantheon). She is perhaps best known amongst the Dwarves of Realmspace, but she does have worshippers in other crystal spheres. In the language of the Dwarves of the Forgotten Realms (used throughout this writeup), her last name is 'Splendarrkuld.'
Haela's portfolio includes luck, joy in battle, Dwarven adventurers, and Dwarven monster kills. Her titles include "The Luckmaiden," "Haela the Hard," and "The Lady of the Fray." She and those who revere her exult in the excitement of battle. This is particularly true when the enemies are traditional foes of the Stout Folk -- orcs, goblinkin, giants.
Haela's alignment is chaotic good, which sets her apart from many of her colleagues, including her superior Moradin. Most Dwarves, and their deities, tend toward law, not chaos, so Haela's followers tend to be somewhat unusual as Dwarves go. Haelans are generally more cheerful (at least when fighting) than a typical Dwarf. They also have a slight tendency to be more mobile in battle, using movement to gain a tactical advantage. Their chaotic natures mean they feel fewer ties to home and family, so their reasons for adventuring are more often for the fun and excitement than to complete specific tasks.
Haela's home is Findar Endar, or 'Cave of Good Fortune'. Her realm is located in The Beastlands in the Great Wheel cosmology (or Dwarfhome in the 3rd-Edition Forgotten Realms cosmology). Her largest center of worship on Toril is Endar Aglandtor (literally 'Cave Sword-Hill', loosely 'Sword Grotto'), in the northern part of Faerûn.
Haela's priestesses, at least in the Realms, are themselves called Luckmaidens. They travel throughout Faerûn, providing what assistance they can to Dwarven adventurers. They help out other races, too, when they are fighting against the enemies of the Dwarves. They often carry spare weapons, which they give freely to those in need. It's customary to respond in kind once the battle is done, but it's rude to give the same weapon back to the Luckmaiden. Luckmaidens in Faerûn often carry a sack of Halfling-made caltrops, a long-standing tradition established when some Halflings gave assistance to a Haelan church.
Haela and her followers fight exuberantly and tenaciously, never giving up until the battle is won, shouting Dwarven war cries and cheers the whole way. Haela herself often manifests on the Prime Material plane -- but only for a few seconds in any one place -- to assist Dwarves in battle. The appearance of even the most minor of Haela's manifestations -- a glow surrounding a Dwarf's weapon -- is often enough to inspire the Dwarves to decisive victory. The discovery of gems such as garnets, rubies, carnelians, and bloodstones is usually a sign of Haela's approval, but if such gems turn to blood when touched, then Haela is not pleased.
In 3rd-Edition D&D, Haela's domains are Chaos, Dwarf, Good, Luck, and War. Her favored weapon is the greatsword, and her holy symbol depicts a sword, point up, encircled with two spirals of flame.