The Necros Knight, much like the Dragonia Knight, is a neutral character in the 30MF universe, in the sense that it is unaffiliated with Liber and Rosan.
It is also described as a 'Death Knight' on its product page and its Core element is "Dark" or "Nothing".

There is a dedicated animation to this model on the 30MM youtube channel, showing a Rosan Knight experimenting on a torso Core and getting arrested for what he's doing, along with possession of a dark tome.
As he is about to be publicly executed, a dark spirit saves him and he finds the tome in his hands. He travels far away and begins to raise the dead, transforming himself into the Necros Knight.

It is thematically connected to the "DLRO Skeletons" kit, which are canonically implied to be his minions, as he raises them from dead silhouettes.

Aesthetics:
The Silhouette 1 body has a Rosan skull face and the plastic is a mix of dark grey and matte black, with grey ring parts. It uniquely features smoky black transparent plastic, rather than the various colored Cores of other Jobs/Silhouettes.

The armor is a very dark grey-brown, with tattered dark blue cloth. It has a classic and somewhat aggressive undead theme with skull pauldrons and a horned skull face mask, with plenty of jagged details.
Interestingly, while a few 3mm holes are left uncovered on the Silhouette, there aren't any to be found on the armor itself (sole exception being on the back of the waist armor, under the cape), signifying that there is not and will not be a Class Up for this character.

Mechanics:
The articulation is the same as any other Silhouette 1 30MF model, which is most of them - In short, it's good and there are no limitations or advantages to this one.

The armor, however, features two wrist armor pieces that allow for the hilt of the included sword to be attached and wrist-mounted, rather than held. I have about a dozen other swords from 30MF and none of their hilts match the notches, it seems to only work with the included hilt. I say hilt, because you *can* swap the blade out for any other blade that has a 3mm peg.
This is not a listed or shown feature, but the hollow shape of this armor suggests this exact intent.

Equipment:
3 pairs of Hands - Holding, fists and relaxed open hands
1 Greatsword with a transparent black gem and a detachable 3mm hilt
1 Scythe - Also has a double sided transparent black Gem, no movable parts
1 set of fairly comprehensive Necros Knight armor - is missing armor on biceps, thighs and calves
1 set of Cloth Parts (in plastic) are also included, including a cape that fits onto other 30MF backpacks
The usual assortment of adapters and Ring Parts, in standard grey

Conclusion:
While this character is very mid-to-high fantasy in its design and clearly has a Japanese style fantasy design overall, the dark plastics look nice and cohesive, unlike some armor combos, especially when you apply a Class Up to them.

The idea of more neutral characters being added to the line is pretty cool and this guy works well as a pen and paper villain stand-in on the table. I especially recommend his skeleton minions (sold separately) which are a 2-in-1 kit with 3 weapon options, that also work well as general props.

The Necros Knight, much like the Dragonia Knight, is a neutral character in the 30MF universe, in the sense that it is unaffiliated with Liber and Rosan.
It is also described as a 'Death Knight' on its product page and its Core element is "Dark" or "Nothing".

There is a dedicated animation to this model on the 30MM youtube channel, showing a Rosan Knight experimenting on a torso Core and getting arrested for what he's doing, along with possession of a dark tome.
As he is about to be publicly executed, a dark spirit saves him and he finds the tome in his hands. He travels far away and begins to raise the dead, transforming himself into the Necros Knight.

It is thematically connected to the "DLRO Skeletons" kit, which are canonically implied to be his minions, as he raises them from dead silhouettes.

Aesthetics:
The Silhouette 1 body has a Rosan skull face and the plastic is a mix of dark grey and matte black, with grey ring parts. It uniquely features smoky black transparent plastic, rather than the various colored Cores of other Jobs/Silhouettes.

The armor is a very dark grey-brown, with tattered dark blue cloth. It has a classic and somewhat aggressive undead theme with skull pauldrons and a horned skull face mask, with plenty of jagged details.
Interestingly, while a few 3mm holes are left uncovered on the Silhouette, there aren't any to be found on the armor itself (sole exception being on the back of the waist armor, under the cape), signifying that there is not and will not be a Class Up for this character.

Mechanics:
The articulation is the same as any other Silhouette 1 30MF model, which is most of them - In short, it's good and there are no limitations or advantages to this one.

The armor, however, features two wrist armor pieces that allow for the hilt of the included sword to be attached and wrist-mounted, rather than held. I have about a dozen other swords from 30MF and none of their hilts match the notches, it seems to only work with the included hilt. I say hilt, because you *can* swap the blade out for any other blade that has a 3mm peg.
This is not a listed or shown feature, but the hollow shape of this armor suggests this exact intent.

Equipment:
3 pairs of Hands - Holding, fists and relaxed open hands
1 Greatsword with a transparent black gem and a detachable 3mm hilt
1 Scythe - Also has a double sided transparent black Gem, no movable parts
1 set of fairly comprehensive Necros Knight armor - is missing armor on biceps, thighs and calves
1 set of Cloth Parts (in plastic) are also included, including a cape that fits onto other 30MF backpacks
The usual assortment of adapters and Ring Parts, in standard grey

Conclusion:
While this character is very mid-to-high fantasy in its design and clearly has a Japanese style fantasy design overall, the dark plastics look nice and cohesive, unlike some armor combos, especially when you apply a Class Up to them.

The idea of more neutral characters being added to the line is pretty cool and this guy works well as a pen and paper villain stand-in on the table. I especially recommend his skeleton minions (sold separately) which are a 2-in-1 kit with 3 weapon options, that also work well as general props.