I'm going to play around with it a little, but they don't show so well with white armor. Tends to look like white instead of silver in pictures. Looking back I do need to add some silver highlights to the black pieces on the chest and thighs to make them pop better.
Try the gun metal silver oil based paint pens. They work insanely well for that deep chipped look. I swear the paint in the pen actually absorbs into the base coat color and really produces a real look.. I'm confident it would work well on white armor too. And don't make a mistake, cause nothing takes it off unless you strip the base coat back off! But thats the fun part of weathering, once you get it down, its hard to make a mistake. I use the pen tip to flow the paint where I want on the edges or surface, then I use upholstery foam to "scratch it" or drag it to what looks like abrasions across the surface. Ask
RandomRanger he uses the same technique I do with the oil based pen. I agree with you, simple silver acrylic paint will just appear white like the rest of the armor, but I'm confident the darker gun metal silver pen will give you knarly looking edge wear. In the attached pic, you'll see the darker metallic silver of the pen vs the lighter silver scratches. What's cool about the pen is it also shifts color at different angles and lights too, which really looks cool on a whole suit of armor that's always moving, thus providing various new angles to viewers. I had to take the pic aiming down like this to catch it in dark gun metallic form.