I think it is the form of a person with raised arms. You also see this in an unrelated tribe in the north, the Kalinga, where their shields are in the form of a stylized human, 2 prongs down for legs, 3 prongs up for the head and raised arms.
I am quite sure it is silver mounts by the look of the oxidation and tradition.
Glad you got this one Bill.
Here are two old threads with great info:
http://www.vikingsword.com/ubb/Forum1/HTML/000548.html
http://www.vikingsword.com/ubb/Forum1/HTML/001052.html