problem with floating shields and spears

[Shapur II]

killerxguy's new spearman model is suffering from the floating weapons and shields syndrome. At first he made 6 shields and 3 spears for those guys to use, he got this syndrome so he deleted 2 shields and 1 spear because he thought the reason was too many varieties of shields and spears.

When he reloads an affected model, the skin is assigned to the abs bone or some other bone I did not set the veritices to. he tried fixing the model into the proper skin modifiers, then he got the syndrome again...any ideas?

NOTE: The model skin modifiers are messed up right after he exports it using KnightErrant's .ms3d exporter/importer for 3dsmax.
NOTE2: he is not sure if this helps, but the 6 shields and 3 spears are all done from scratch, with the skin modifier and UV map also done from scratch.