Nightshroud Warhammer fantasy battle 8th edition vampire counts magic item overview
The magic armour Nightshroud whilst keeping a similar theme has changed somewhat from 7th to 8th edition warhammer. Its points cost has increased, it now adds an additional +1 to the wearers armour save and causes any model in base contact to lose the strength bonus from any weapon magical or otherwise they are wielding. It also causes them to gain the always strikes last special rule, this synergises well with the quickblood vampiric power as it ensures you are more likely to get re rolls to hit.
These rule changes makes it more effective (and of course more expensive). It can still be worn by both vampire lords, hero level vampires, master necromancers and necromancers, it may also be worn by wight kings. It is of more use to vampire characters as they can boost their armour save quite easily with the addition of heavy armour, shield and mount. Necromancers are wizards and should ideally be avoiding combat where possible.
Pros and cons of nightshroud
Pros are that it can be very effective against the right armies/units many elves for example lack a high strength without boosting it with a weapon of some kind. This would make for example high elf sword masters requires 6's to wound a vampire lord whilst giving you your full armour save. Making your enemy's lose their strength bonus does of course also effectively increase your armour save making it best combined with heavy armour, shield and a mount (preferably barded if possible). It also gives a powerful combat orientated vampire a good chance to cut down their foes before they even have a chance to retaliate.
As its effects are now base contact it also affects your mount. This can make a zombie dragon extremely difficult to kill consider ogre kingdoms ironguts for example they would normally wound a zombie dragon on 4+ so would quickly cause it severe damage, when ridden by a vampire lord wearing the nightshroud this becomes a to wound roll of a 6.
Cons are it has little effect against models with a high basic strength or gaining additional strength for a spell or the potion of strength. Also it is expensive and does not grant a ward save so offers only the additional bonus to the armour save of the wearer against missile and magical attacks so potentially leaving you vulnerable to these. There are also some special characters such as the Emperor Karl Franz and the Everchosen Archaon whose magical weapons combined with armour and ward saves could potentially survive your attacks and kill you in return.