I was asked to expand a bit about dvergar awhile back. Apologies for the rambling nature of this post, as it’s a bit of an info-dump, rather than sticking to the original question about the four stags.
There’s some confusion about whether the dvergar and svartalfar are the same beings, which I’ve covered before. In addition to this, a large part of what we know about the dvergar is found by looking not only at the Eddas, but the sagas, later folklore, and their names themselves, which are often descriptive.
We know that the dvergar are crafters. Not only do we have the story of them making a large number of the Gods’ treasures, including Mjolnir, but also the fetters of Fenris-ulfr and the mead of poetry (as their crafting prowess is not limited to smithing). A number of mentioned dverg names also translate to smithing or skill-related terms. They are also linked to mining, and the sølvmora, gruvfrökenm and gruvrå may all be late folklore versions of dvergar. They may guide and protect miners, or decide to guard and protect the precious ore in the earth and attempt to sabotage the mines and kill the miners. Interestingly, all three of these sorts of spirits are female.
Dvergar are also associated with death and sickness. While this becomes more obvious in folklore as time goes on, where we have charms against them, or use the stones and metal trinkets associated with them to ward off the sickness they might inflict and name sicknesses for them (like with dvergskot), but you run into dverg names that are indicative of death. Grave Treader (Haugspori). Corpse (Nár and also possibly Náinn). Blue-Black (Bláinn), which was commonly used to describe corpses or a draugr or haugbui (types of undead). Snorri interestingly chooses to describe their origins as being maggots festering in the flesh of Ymir, rather than the creation story listed in Voluspá, which is just one more piece of death imagery. They also tend to be listed as gray or pale-skinned, not merely because of where they live and how they avoid the sun, but to the point of looking deathly. Thor comments on this paleness and jokingly asks Alviss, during his visit, if he’s “laid with the dead recently” (“Hví ertu svá fölr um nasar? Vartu í nótt með ná?”). Equally interesting, Thor comments that this deathly appearance makes Alviss resemble a thurs. The association of dwarves with a short stature and a grotesquely ugly appearance only occurs in later folklore and is nowhere indicated in earlier accounts.
Like the dead, dvergar live under the earth and in the mountains. This concept is basically scattered all over the sagas, amongst skaldic kennings (dagskjarr, holmleggjar hilmir, Regins skáli, fyrða fjarðleggjar, veggbergs vísir, dvergrann, etc), in references in old poetry (pay attention to how Alviss describes what the dvergar call different things), and in later folk belief and ballads. Folktales are full of dvergar who are miners or mountain dwellers, tell about catching dvergar by watching for them in front of the rocks they live in, and terminology that references their chosen abodes (such as dvergmáli for “echo”). There are references to dwarven doorways through rock even in Voluspá (stynia dvergar fyr steindurom), and in folklore it’s suggested that these aren’t always just doorways into a dwelling place inside the earth, but sometimes ones to a different realm. They can also trap their enemies in stone, as happens to King Sveigðir in Ynglingatal. Dvergar are also associated with stones by the way they turn to stone in sunlight, as happens to Alviss in Alvissmál.
Dvergar are sometimes thieves. Fjalarr (“deciever”, fittingly) and Galarr take Kvasir and turn his blood into the mead of poetry. Jacob Grimm has a list of thieving dwarves in his Teutonic Mythology, Álfaríkr is described as “the great stealer” in Thiðrekssaga, and there are a few other dwarf names that suggest thievery (Alþjófr, Hléþjófr, etc).
Dvergar are known for their wisdom, rather like some jotnar. Alviss, Fjolsviðr, Ráðsviðr are a few examples of dvergar named in ways that suggest wisdom or great learning. Dvergar are also known for their magic powers. Þióðrorir is a known chanter of magic charms, Alviss is mentioned to know the key to secret languages, and the sagas mention dvergar possessing amazing powers of healing, cursing, and magical craftsmanship. Aside from Snorri’s account of the dvergar “as maggots” and Voluspá stating that they were formed from the blood of Brimir and the bones of Bláinn, there’s also the story of two dvergar, Durinn and Móðsognir, who shape other dvergar out of clay and breathe life into them. Additionally, Snorri tells that some of the “lesser norns” who shape the lives of humans are the “daughters of Dvalinn” and, thus, dvergar women. Galarr, one of the dvergar who murders Kvasir and brews the mead of poetry, has a name that means galdr-singer. In Egils saga, Egill has his cut off arm completely restored by a dvergr, as well as a sword, after he gives the dverg a finger ring as a gift.
There are also the four dvergar who hold up the sky – Austri, Vestri, Suðri, and Norðri (East, West, South, and North, respectively) – and four stags – Dáinn (Died, or Dead One), Dvalinn (Slow/Sleeping One), Duneyrr (One with downy/brown ears), and Duraþrór (Door-Stubborn) -who graze on Yggdrasill’s branches. The sky is referred to as Niðbyrðr Norðra, “the burden of the relative of Nordri”, reinforcing this idea of dvergar serving as support for holding up the sky, and there’s a parallel for this in old building terms. Among the Icelanders, Danes, and Norwegians, “dvergar” could refer to the small blocks of wood that stood on the rafters and held up the main beam of the roof. (See Terry Gunnell’s Hof, Halls, Goðar, and Dwarves: An Examination of the Ritual Space in the Pagan Icelandic Hall , p. 21) Unfortunately, we don’t have more information regarding these dvergar, and it’s unclear whether the stags are meant to be a benevolent natural force (the source of dews and some rivers) or whether, with the dvergar association with death and decay, they are meant to be a mirror to Níðhöggr gnawing at Yggdrasill’s roots.
Curiously, while alfar and dvergar get separated into distinct families, there’s also some blurring. Dwarf names in Voluspá have alf in them (Alfr, Gandalfr, Vindalfr). Volundr is a master smith that is called ruler of elves (álfa ljóði) and prince of the elves (vísi álfa). Dáinn appears as a dvergr in some spots, and as an alf and teacher of the alfar in Hávamál. Alberich, or “Elf-Ruler”, is a dvergr in the Nibelungenlied.
Mead is associated with the dvergar through various kennings. It’s called the “drink”, “cup”, “sea”, and “wave” of the dvergar. (Regins drykkr, Dverga drykkia, Dvalins veigar, etc).
Aside from shapeshifting into deer (as mentioned above) and into fish (as with Andvari, who takes the form of a pike), dvergar are associated with spiders. Svergsnät is listed by Jacob Grimm as a Swedish folk term for a cobweb. There are also a number of dwarf names that refer to wolves (Hlévargr, Hljóðólfr, Hleðjólfr, Aurvargr), although it’s more likely that this has to do with being destructive, trecherous, tricky, or operating outside the normal laws of human civilization, particularly as “vargr” is the term used.
One shouldn’t try to wring treasures and favors out of the dvergar through threats and unfair dealings. Cheating the dvergar doesn’t end very happily for Loki, and Andvari and Dvalinn both put terrible curses on the treasures that get unwillingly extracted from them. If one does favors for them, they are willing to repay the debt with magical skills or some of their craftwork.