In the Louvre, there is a relief from Apollonia Pontike (modern Sozopol, Bulgarian coast). Reference CA 1748. I noticed it and photographed it a while ago, and couldn't find my photograph. There is an excellent one on a photo sharing "website".

http://www.flickr.com/photos/7945858@N08/3502689902

The hoplite on the left is blowing a horn. He has some form of composite breastplate; you can also see very clearly that he is carrying his shield on his back, using one of the mysterious "auxiliary cords" that usually hang slackly off rings round the inside of the shield.

The hoplite on the right--whose mouth is open in a rictus of aggression-- holds a spear in his left hand. His right grasps a mysterious object. I distinctly remember this being described on a label as a sling pouch wrapped around a stone.

(For a clear image of a hoplite slinging, discussion here:
http://slinging.org/forum/YaBB.pl?num=1360162104/0
Aryballos from Delos)

…identified as a sling here !

http://commons.wikimedia.org/wiki/Template:Musée_du_Louvre:Inventory/CA#mediaviewer/File:Frieze_plaque_hoplites_Louvre_CA1748.jpg

and here too

http://cartelen.louvre.fr/cartelen/visite?srv=car_not&idNotice=9875

https://www.academia.edu/1464036/Présentation_générale_de_l_histoire_et_de_la_topographie_d_Apollonia

From the excavations on Sveti Kirik, island off Sozopol: probably architectural terracotas, perhaps shrine of Apollo Ietros.

The sling identification was proposed by G. Seure, Rev. Arch 1924, p. 307-316 (I think).