Random idea that hit me before I fell asleep: What if a d-pick was able to break one or two blocks in faction land before breaking? Or just in general, allow block changes; however, make the permissions tool specific and the penalties almost or completely destroy the tool.
Do you mean breaking a block in faction land with a D-pick will take off 50% durability? ...Or do you mean just breaking two random blocks in faction land destroys the pick without durability changes?
Breaking a block would instantly destroy or set the pick's durability to half. Too much to allow major griefing but enough to allow raiding. Perhaps things like chests would be exempt from the rule. It would be a bitch to code though.
You wouldn't be able to place blocks in other faction's land; however, people would start making bases out of chests because of the plugin. Abandon thread! Too much work for admins or server mods!