I have a T. cupreus that dropped a phantom sack about 2 months ago.
a) this confirms maturity right? A little stumped as she is only about 9cm
b) does the drop indicate that she now cannot be mated until she has molted?

I'm fairly sure that the answer to both questions is YES but I need assurance.

Thanks bunches!

If she has made a phantom sac she is sexually mature to be mated and bred.

If i were you i would wait for her to molt again to attempt mating, im pretty sure that
for that small female it would take alot out of her to produce a fertile or phantom sac.
I would rather wait for her to molt and regain her strength. Rather be safe than sorry.

Agreed with Dave.
You could mate her before she moults, and she might drop, but think it will definately take a lot out of such a small female.
Rather wait for a moult IMO.

I have a female T. violaceus that was sucessfully mated by Hendrik. She is also only 9cm.

A female only has to be 50% of its full grown size, to be able to mate and breed.
The only thing about small females is that the alot easier to breed BUT they will make a
smaller egg sac and the stress on a smaller female is much more.

Dave wrote: A female only has to be 50% of its full grown size, to be able to mate and breed.

For certain species I have found it can be as much as a third of the full grown size (Augacephalus junodi)