Looking into them for a possible reintroduction.
So far I got ring of Kahjiits and the. Lord's mail if. Not wrong....
Others ?
A: http://www.uesp.net/wiki/Lore:Artifacts_A
B: http://www.uesp.net/wiki/Lore:Artifacts_B
C: http://www.uesp.net/wiki/Lore:Artifacts_C
D: http://www.uesp.net/wiki/Lore:Artifacts_D
E: http://www.uesp.net/wiki/Lore:Artifacts_E
F: http://www.uesp.net/wiki/Lore:Artifacts_F
G: http://www.uesp.net/wiki/Lore:Artifacts_G
H: http://www.uesp.net/wiki/Lore:Artifacts_I
I: http://www.uesp.net/wiki/Lore:Artifacts_I
J: http://www.uesp.net/wiki/Lore:Artifacts_J
K: http://www.uesp.net/wiki/Lore:Artifacts_K
L: http://www.uesp.net/wiki/Lore:Artifacts_L
M: http://www.uesp.net/wiki/Lore:Artifacts_M
R: http://www.uesp.net/wiki/Lore:Artifacts_R
S: http://www.uesp.net/wiki/Lore:Artifacts_S
T: http://www.uesp.net/wiki/Lore:Artifacts_T
U: http://www.uesp.net/wiki/Lore:Artifacts_U
V: http://www.uesp.net/wiki/Lore:Artifacts_V
W: http://www.uesp.net/wiki/Lore:Artifacts_W
That appears to be a complete list of everything the UESP considers to be an Artifact that wasn't included in Skyrim. Hope it helps.
Oops. Forgot that Umbra was also destroyed.