For the leadership stat - I actually tried both.
When I agreed to help I played until the choice to improve a second stat and even when I chose the second one it (leadership stat) didn't go up.
When I didn't agree to help him and chose it as a second stat to raise I played up until the part where we choose how we feel (about our family) and the stat didn't go up. It didn't matter if I chose Queen Elora or Sir Oren to go with first.
Just now I also tried agreeing to help Prince Irus and then chose not to raise another stat - this is the only time when the leadership stat went up. (at least from what I've tested)
Hope that wasn't too confusing of an explanation :')
For the locket - Ah, alright! Thank you :>