So I found four artifacts. the artifact of honor, glass, kin, command. they are all pretty cool but I cannot create a page (at all) or edit the items page to add info about them. Therefore I will write what I know here.
Location: Desolate forest.
How to reach: in one of the versions of desolate forest the bottom left end of the level is blocked by blocks, you can see the artifact if you look behind the blocks but the only way to reach it is to go to the nearby jumpstream thing that leads up to some ropes. Instead of jumping to the right you should jump to the left and into the small passage. continue along this path which requires some jumping and you should reach the artifact (note that the best class to use to get this is the miner, since he has increased mobility over the other classes).
Effect: All enemies spawn as elites.
Location: Dried lake
How to reach: One of the dried lake version has a destructible wall to the far right of the level. You can see that it is destructible because of the cracks in it. Jump to the platform which the cracked wall lies on (Commando with jetpack or a miner is needed for this). shoot the wall a couple of times to destroy it and then walk into the newly opened cave. Inside you'll find some strange buttons on the walls. You must hit all buttons in quick succesion to make the artifact appear.
Effect: Only one type of enemy spawns per stage (i.e. if the game chooses lemurians they will be the only enemy to spawn. when you activate the teleporter, there will be no boss, just the selected mob (unless the selected mob was a boss).
Location: Frozen tundra
How to reach: (the bridge must be broken as far as I know) on the left cliffside there is another destructible wall near the top. destroy it and go inside to find another button puzzle, this time with a bit more time for you to complete it. The puzzle can be a bit hard since you need to climb from rope to rope at the final button. as always I recommend the miner for it. When you have gotten all the buttons you jump down to find the artifact in the same kind of stargatey structue you found Kin in.
Effect: deal 500% damage but have 10% health
Location: Hive cluster
How to reach: This one is (atleast according to me) one of the easier ones. It is located in the top right corner of the level. climb all the way to the top using the large goo thingies. up there you should see some pink glowing ropes that seem to phase in and out of existence. Jump up and grab these, don't worry about them disappearing, they just go invisible. Jump from rope to rope until you reach the artifact.
Effect: Items are no longer random (THIS ARTIFACT IS AMAZING!!!!!1 (ok, but seriously, it's amazing. every time you open a chest, an item appears from a statue or you choose the ? option in a store you will, instead of an item, get a box. If you press a on the box you will get a selection of a HUGE amount of items. the rarity and type (passive or usable) depends on the colour and shape of the box).
I will update this list when I find more artifacts.