Prevalence (or perhaps: ubiquity) is difficult to measure, since we don't have descriptions of combat that are detailed and reliable enough to give us any sort of idea at all. Our next best bet is grave data, although there's no reason to assume people were buried the way they lived. I have a data set of 723 Viking-Age graves from Gotland, and perhaps it's best to jump straight into the numbers:

20 of 723 graves on Gotland have arrowheads. 25 have swords or parts of swords; 19 have a seax (a single-edged sword, like a machete); 24 have spears; 34 have axes; 7 have shields. Two initial caveats: (1) These figures reflect the numbers of graves that include these items, i.e., I counted the number of Gotland graves with swords, not the number of swords buried on Gotland. (2) Some graves include more than one type of weapon, such as an axe and a spear, and so these graves are counted twice in the list above. I created my dataset for a different purpose, so I'm limiting myself to the quick analysis I can do (i.e. counting) without combing through or recreating data columns.

Those are the problems with the data itself. There's also the problem of representativeness. Do the artifacts in grave represent the things people would have had in life? Probably not. For example, Gotland picture stones from the same time seem to represent almost everyone wielding a sword. It's easy to assume that the stone carvers were just looking for simple symbols of warrior identity as they carved their figures (although they might have other reasons for doing so). At any rate, it makes the diversity of weapons buried in graves stand out, as well as the apparent absence of shields.

Some of this is likely due to the ways archaeologists work. Especially during the early years of excavations in the 1800s and early 1900s, archaeologists sometimes picked up only the big fancy items and might easily miss a fragmented spearhead or the smaller remains of arrowheads. In England, we know that some early antiquarians sold the metal from a boat grave at Sutton Hoo to be turned into horseshoes. In Sweden, at least one excavator used dynamite so he could clear three or more rock-covered burial mounds each day. These aren't great conditions for counting individual artifacts, although almost all of the graves in this data set come from the 1930s–1970s.

But the bigger source of difference is probably that people made all sorts of decisions—some of which we might never understand—when they buried their dead. Perhaps you want to keep a sword in the family, so you bury your dad with an axe instead. Or perhaps you've got certain beliefs about Odin and spears, and so you bury your sword-heaving dad with a spear instead. Maybe your dad once hunted a boar, so you bury him with his hunting spear, even though he'd never harm another person and certainly never fought in any battles.

Where does this leave us? Well, it seems that arrows were just about as common as other weapons, including swords, seaxes, spears, and axes. Since multiple kinds of weapons appear in some graves, we can estimate that about 25% of people buried with weapons on Gotland were buried with arrows. That figure might reflect how prevalent archery was in combat, it might reflect the practice of bowhunting in Viking-Age Scandinavia, and/or it might reflect beliefs about the what meanings or symbolism were behind different kinds of weapons.