As a Death Knight, your body is dead and the nerves that once ran through your body have fallen as dead as you. No longer do the synapses transmit electrical pulses through your body as the nerves have died. This can be both an advantage and disadvantage for you in many ways. Still, your unholy energy uses these paths to control your now unliving body. Instead of impulses being sent from the brain itself, the impulses are now sent from your runeblade. For this reason the runeblade must always be kept close to your body lest you become weak and immobile. One major benefit however is that so long as the runeblade is near any part of your body, the unholy energy can travel through the nervous system. This will allow you to continue to move despite wounds, appendage loss, or damage that would normally immobilize a living body as there is no central point of control from the unholy energy. Instead, your unholy energy can control from any point of any part of your nervous system.
As stated earlier, your nervous system is dead and because of this you will no longer be able to feel the sensation of touch or pain to the same degree. The unholy energy that now moves your body however, can still transmit a small amount of sensation as it travels through your body. It’s possible to train yourself to ignore this sensation or you might not even realize it was there, but through fighting you may feel the sensation as you are hit. The same principle applies to feeling hot and cold and this is beneficial. Your entire body is dead and for some is colder than others. Without the nervous system however, you will not be able to feel your frigid cold body but neither will you feel heat. Since the unholy energy is flowing through your now dead nervous system, a mastery over runic unholy power can yield interesting results. Using your runic unholy power, you can temporarily restore the severed nerve endings that once let you feel touch or warmth.
Taste / Smell:
Without having a functional brain or nervous system, there is nothing to correlate the sensations of taste and smell. As with touch however, a sense of taste or smell can be brought out through a mastery of runic unholy power.
As a Death Knight, your organs are no longer fully functional. Any way that your body worked in the past, it is no longer going to work that way again. This raises several points about how your non-functional organs will act and how their old habits will be handled.
Cardiovascular / Heart:
You may remember a time when you could put your hand over your chest and feel the beating of your heart. Well, those days are now over. The heart, along with the rest of your cardiovascular system, has fallen all but silent. Without the beating of your heart, blood is no longer being pushed throughout your system. Though it is possible for it to flow still, it would do so without being pressurized and move at a snail’s pace. The blood flow is also the reason behind your now frigid body. You may not notice it yourself, others surely will have, that your body is now cold, maybe freezing to the touch. To add to this, a mastery of runic frost power gives you further control over your cardiovascular as you can completely stop your blood and vary its temperature. It may still be impossible to warm yourself, but taking away the temperature can make you less dangerous to touch and completely freezing your blood can prove a useful combat ability. With your blood frozen completely, you can use your body as a shield to completely nullify an otherwise successful slicing attack. Either way, keep in mind that when you are attack your blood will not spurt out as it once had as there is no pressure left. Depending on your own abilities, the blood will either trickle out or be frozen completely at the wound. It is good to practice freezing your blood because remember, you won’t be able to clot.
Digestive Track / Eating:
Your stomach is still filled with a powerful ichor like acid that can break down anything that you’re willing to put in your mouth. Unlike before however, the digestive track does not function and you will not be able to conventionally remove this material from your stomach. Your intestines no longer perform their functions and to deal with digestive materials the only way is really up. Still, there are uses for eating which should be heavily considered. Though you do not need to eat for sustenance, you can learn abilities to make use of what you do consume. As you learn to utilize your runic blood power, you will find that you have the ability to pull that energy from what you consume into your own body. It may not seem appealing to you at first, but the rotting flesh of the once living is filled with an unholy energy which can be pulled to heal your own undead body. In turn, consuming the flesh of the living will serve a similar purpose but require greater quantities. If you kill a living creature, it is best to let the corpse rot for at least a week before consuming. Just be happy that you no longer need to rush off due to bowel movements.
Lungs / Breathing:
Old habits die hard and you may notice that often times you are taking in breathe as if you were actually breathing. Your lungs even expand and in the cold you can see your breathe freezing before you. Despite what you may think however, this is more of a habitual act than one that you require. Since your body is dead, your cells are dead, and your body does not need oxygen to keep it alive. There is really not drawback to not needing breathe as it allows you an amazing amount of advantages. You can survive underwater or in the vacuum of the twisting nether indefinitely, willing yourself to stop drawing breathe will make you immune to any form of airborne gas (poisonous, incapacitating, plagued), and this comes in handy when someone attempts to choke you during a fight.
As with everything else in your body, your muscles have undergone myopathy and are comprised of dead cells. Due to the fact that the muscles are dead, it means that they can no longer be trained to strengthen and grow naturally. On the other hand however, they also no longer fall to the fate of exhaustion. One of the most notable points of being a Death Knight is that you have unlimited stamina and will never feel tired again. So long as you wish to keep moving, your body will support that as best it can.
Being knocked unconscious is something that you will no longer have to worry about. This is something brought on by causing trauma to the brain, a considerable amount of pain, or a drop in blood pressure. Since you brain cells are already dead there’s nothing that can affect them further and without the sensation of pain or the fact that your blood is already unpressurized, you cannot be forced unconscious. Let your enemies hit you in the head as much as they like, it will only give you motivation.
Thought it is possible for a Death Knight to sleep, there is no need. A Death Knight does need sleep or rest as there is nothing in their body that has a need for recovery.
Poison / Venom:
Due to the nature of poison and venom, you will find that your body has built a resounding immunity to them. Poison may still have some small range of affect, as your dead cells will still absorb the poison through osmosis.
This attacks the blood stream causing the blood to clot, blood pressure to drop or breaks down the blood vessel to rupture and the victim to bleed out. Being a Death Knight, you’re not going to be affected at all by a Haemotoxin. You may have already stopped your blood flow, which means that the blood clotting won’t change anything and there is already no blood pressure. Should the blood vessel rupture it is no different than any other wound as you don’t have any need for the blood that resided inside. A Death Knight skilled in runic frost power would be able to completely freeze their blood vessel and counter any rupturing.
This attacks your nervous system and can cause various systems of your body, namely respiratory, to shut down. Again, as a Death Knight, your bodily systems have already been shut down completely. Though the toxin may travel through your nervous system, which is currently being used to transfer unholy energy, there is nothing that can be shut down and the dead cells of the nervous system are immune to further necrosis. Without brain function, the neurotoxin also has no end point to attack. A Death Knight skilled in runic unholy power would be able to completely negate the flow of the neurotoxin through their nervous system by attacking it with their unholy energy.
This attacks the tissue and muscle cells of the body in an attempt to break them down and force them to undergo necrosis. Being a Death Knight you are completely immune to any form of Cytotoxin as all of your cells have already undergone necrosis and myopathy. This gives you immunity to the effects of paralysis.
Alcohol is absorbed into the blood stream from the stomach and small intestines and can be processed by the liver. Since your digestive system and liver don’t work the way that once had, they no longer take a part in breaking down the enzymes of alcohol. Continuing this, alcohol is not absorbed into the blood stream effectively since there is no or very slow flow of your blood. Due to this, the alcohol, like most things, will remain stagnant within your stomach until expelled. You are no longer able to feel the effects of alcohol such as intoxication or loss of mobility.