It's actually fairly explicit in the Torah, specifically in Numbers chapter 35. The Mosaic code there established cities of refuge to which killers were to be allowed to travel and be judged, where they would be free of revenge from those wronged until the priests decided whether their offense was murder, manslaughter, negligence, or accident, and imposed the appropriate penalty.
Since time loops are stable, no reason not to try. Even if Mr. Counsel is Lucius, the most stable time loop is that Lucius doesn't believe the Patronus and gets killed anyway, and then Harry can at least truthfully tell Draco he tried.
I was wondering if one of the things Harry would do with his extra hour was a Patronused message to Lucius to "Stay where you are, remain silent, do not respond to the Dark Mark, for one hour, if you want to live." Or even better, a message to Draco to send that message to Lucius, except Draco is probably still sleeping off Harry's stunner.
In any case, under the circumstances, Harry might be able to trade the whole sad story, including confirmation of Dumbledore's ordered killing of Narcissa (now that Dumbledore is gone) for Draco's forgiveness.
Because it's hard to be seen as on the light side when you decapitate 38 adult wizards in an instant? Fame is harmful, not helpful, to Harry's goals. Better to make it look like Voldemort managed to cause a magical backfire that killed all his minions in a failed ritual involving Hermione. To go back to the Azkaban chapters, the perfect crime is the one that is declared a tragic accident and closed.
I like this, and you can resolve "HE IS THE END OF THE WORLD" by combining the rule that prophecies are meant to be heard by those they affect and to cause their consequences, and that to Voldemort, his death is the end of his world. So HE IS THE END OF THE WORLD is true for Voldemort, because Harry's killing power can be the end of Voldemort's world.
Combine this quote, partial transfiguration as the power Voldemort knows not (both true and foreshadowed by Dumbledore's reaction when Harry first revealed it), the previous weaponization of partial transfiguration when Harry transfigured a cross-section of the troll's brain into acid, the shaping exercises as a Chekov's Gun, and another Chekov's gun being Harry's resolution to drop the Batman "no killing" stance if the enemy killed again.
Harry wordlessly transfigures an atomic-thickness line of material from the tip of his wand through his clothes and the ground to all Death Eaters and Voldemort, let's say transfiguring their skins to acid. That would cause blood to spill in litres, a fraction of a line of silver, and probably a scream.
Let me give you some more immediately useful advice: a recommendation. The New York Diamond Center at 65 Broadway (ignore the big-sounding name, it's a small shop with an expert salesman) is where I bought both my engagement ring and our wedding bands. The salesman will provide useful and professional advice about the relationship between price, size, and quality. Importantly, he sells loose diamonds and orders the settings separately. You will get the GIA certificate from him for any diamond you buy. And then you also have your seller already picked out for wedding rings.
Do try to get an understanding of your girlfriend's taste before going to pick out a ring and a setting. It should not be a surprise or a secret that you're planning to propose, so talk about her taste in jewelry, whether she would prefer a more traditional round cut or one of the other more unique cuts, band color and design, etc. Also get her finger sized somewhere--even within average ranges, her finger could be anywhere from a 7 to a 9.
One important thing to remember on price is that it roughly scales with the square of the diamond's size in carats, so that a 1 carat diamond will probably be about 4 times the price of a 0.5 carat diamond. The guy I recommended will show you what diamonds of different quality look like so you can see what you're paying for.
Note that you can and should insure your diamond on your renter's or homeowner's policy. Your insurance broker will want a copy of your receipt and your GIA certificate.
One last tip, if you're planning to propose out of town and need to keep it hidden through airport security, sneakily transfer the box from your pocket to inside your shoe, and then back to your pocket on the other side of the scanner. And then make sure it's in the opposite pocket from your girlfriend on the flight so that the jewelry box digging into her hip doesn't give it away.