I would be in favour of a system in which some merit is generated to give for all users. That is, a newby may get 1 merit every month to give away, a junior 2 merit, etc...
Leaving Junior Members without signature has been a bad idea, I am sure many of them were in the middle of a signature campaign and now they will loose all their effort. Even a "grace period" of 1 month on this regard would have been a life saver for many.
I think the idea is that the ability to give merit is a privilege, not a right. You earn the ability to give Merit based on the Merit that you've earned from your efforts in helping the community.