Denying arms is explicitly forbidden by the 2nd Amendment. And since denying arms to felons is not a necessary part of the justice system described elsewhere, there is no conflict there. (See how this works?)Torture is explicitly forbidden by the 8th Amendment ("Excessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments inflicted"), and since torture is not a necessary part of the justice system described elsewhere, there is no conflict there.
You are describing "arms control", which comes from legislation, not the Constitution or jurisprudence. A court did not make certain weapons inaccessible, Congress did with its powers to regulate even rights, which the courts have found to be reasonable for the safety of the general public.Not quite. Scalia was quite clear in Heller about especially dangerous or uncommon weapons being justifiably restricted. This is a nod to the reality that something uncontrollable or intrinsically unstable with potential for predictable collateral damage, needs to be subject to additional controls (and security) for the safety of the general public.
The 2nd Amendment isn't more special than the 8th or the 1st. If the Congress makes a law that is an exception to the prohibition on unusual punishments or due process (Guantanamo), and the Supreme Court finds it reasonable, then it will be no different than the felon or wife beater exception to the 2nd.