There are three types of ranged weapons - Bows, Crossbows, and Guns. But there will only be two specs that use ranged weapons in Legion, and that means only two artifacts. Marksmanship will get a bow and Beast Mastery will get a gun. But for those of you who who prefer firing bolts instead of arrows or bullets, never fear. Both Thunderstrike and Thas'dorah (the gun and bow, respectively) will have a variant look that makes them each into Crossbows.
The fact that these weapons can change to a similar but different type actually raises some interesting questions, namely whether one could have done that for other weapons. As far as I can tell, every other artifact weapon will stick to its weapon type. Warriors of all types will be using swords, and there isn't a single two-handed mace among them. The sole axe is the Blood Death Knight artifact, and I don't believe there are any Wands to speak of (though the jury's out on what the hell the Demonology artifact counts as. If I had to guess an existing one, I'd say off-hand item, but that leaves the question of what's in the main hand totally open - and while there are off-hands for several casters (namely Shadow, Fire, and Holy Paladins - not counting shields used by Elemental and Restoration Shamans) none of them have been the "main event" as it were.
While obviously the Ashbringer is one of the most iconic Paladin weapons in the canon, it is a shame to me that there isn't, for example, an option to let Retribution use a two-handed mace with a classic warhammer (technically "maul") look.
Still, there are definitely tons of options for many of the artifacts, giving you a lot of leeway on how you want to represent the item. For example, Icebreaker, the Protection Warrior sword/shield combo, in which the shield is made from one of Neltharion's (pre-Deathwing) scales, can look like a big dragon scale with some Vrykul decoration, or you can go full-Deathwing to have the cracking-elementium look he had in Cataclysm with lava pouring out of it, or alternatively you can go for a more skull-and-bone motif, befitting the Vrykul and their relationship with the Scourge.
Some artifacts are inevitably going to get cooler options than others (personally I'm not really crazy about any of the Subtlety dagger variations, though I'll have to see how they really look in-game) but Blizzard knows that they're kind of forcing people into using these weapons for the whole expansion (and mind you, I'm excited about the system,) so they want to make sure that we get lots of options to personalize them.
And just for the record, every variant appearance has several color schemes, so you can give your Warlock artifact a nice Legion-y green fire appearance or you can go for the classic black-and-red/orange fire and brimstone look.