[kosta50]

As I'm seeing it, part of asceticism is strengthen our ability to use instincts properly in a healthy manner, and to gain the freedom of restraint as it were

I am not sure there is 'freedom' in restraint. It would seem just the opposite. Restraint from abuse, however, is freedom from evil.

[D-fendr]

If you're unable to restrain from acting on your passions, if your instincts have greater power than your restraint - or your ability to be indifferent to the lure of abusing your instincts - then you're not free. They're in control rather than your mind and heart.

"Freedom of restraint" refers to this. Maybe more accurate to say "freedom of being able to choose restraint."