[@Crow] it's mostly there to restrict strong powers and to also be difficulties your character might over come as they become more experienced and grow in power.  Like if you want to be able to raise the dead for whatever reason, that can be kind of strong, but if you add that the corpses must be fresh and that they must be ritualisticly prepared it would make it more in line with the capabilities you would have at the start. 

So I would say it is a 'soft' requirement, you really only need to include it if you or I deem your characters power too strong and also helps give me an idea of how your character might grow stronger over the course of the RP.