helping others develop their "self authority"
I have a couple friends who are subservient and let people treat them badly.what type of things do I do/say to develop their strength
You can explain/show it to them by demonstrating it. That's a great way. You can also point things out here 'n there and simply tell them that person is sort of encroaching, explain how and then quickly explain how to handle it another way. Don't be too preachy or long-winded.