Couple of things. First, gravity is a PIA in clothification. About the best you can do to reduce slippage is to turn up friction a lot, and turn down density. It is almost impossible to get something like a dress not to slide down a character's hips. In fact, last time I did a pair of shorts I stood the figure on her head! You can pin the thing up with constraining. This is all done in cloth room. Edit the groups, select some verts along the waisband adding them to Constrained (or Choreographed, depending on what you are doing pose and animation-wise). The cloth will hang funny from constrained vertices, but at least it won't slip to the floor. Think of it like super-gluing parts of the fabric directly to the body. Second, and much more troublesome, it is depends on the mesh itself, and the model. An armored skirt of the Roman type, with separate leaves, could be a real pain. You may need to do some creative stuff here. The thing I would try first is, if there is an underlying skirt, to make that and only that dynamic, with the overlying greaves (or whatever they are called) Soft Conforming groups. That way they just follow what the skirt is doing, and don't try to calculate themselves. It is possible, if there is no skirt, you will have to make one. Past this point I can not advise, not having the model to look at myself. I suspect, however, that the leather parts will have thickness, and that will throw the cloth engine off in various horrible ways.