So, power levels. I'll be going from top to bottom, from level 100 to 1.

level 100: Sanguine and Oliver, but add to that the skills not available to the npc's and their equipment and they're basically above everyone else.
Level 100 at boss level (meaning they're meant to be fought by 5~10 people at the same level): Daniëlle.
Level 85~95 at boss level: Around 3~4 random npc's in the monster arena and guild army.
Level 85~95: All the other leader NPC's. (the two army commanders and the arena woman are at boss level.)
Level 65~80: Maids, and once again around 20~30 npc's in the arena/army. 
Level 40~65: Most other servants and soldiers in the army.
Level 30~40: The remaining few servants (like the barkeep or the slaves providing Sanguine with blood)

People from the world itself:
100+ and immortal: The gods of this world.
50~80: Dragons and beings like angels/demons sent directly by the gods.
50~70: The top from a hidden country where intelligent monster races live and are ruled by half dragons. The most powerful country in this world.
25~45: Powerful rare monsters like elder vampires, liches, giants, drakes, etc.
20~45: Other beings from said monster country.
30~35: The top 10 adventurers of all the human countries combined.
20~28: Powerful adventurers and top soldiers of the kingdoms.
15~20: Average adventurers and soldiers like squad commanders.
15~20: Average, uncommon monsters like trolls, ogres, normal vampires, etc.
5~14: Starting adventurers and your average foot soldiers.
5~14: Weaker common monsters like goblins, orcs, zombies, etc.
1~10: Normal citizens, though the higher level ones usually have trade skills like blacksmithing, alchemy, farming, carpentry, etc. And are considered highly skilled or masters in their craft.

Don't take this as 100% fact. It's just a quick overview of the general idea of how I see the world's power is distributed in terms of battle strength. As you can see, Sanguine and Oliver are at the top. Though the boss level npc's would beat them if our duo doesn't come prepared with proper items/gear and tactics. And also as you can see, while the maids/servants wouldn't be able to beat Oliver or Sanguine, most would be able to survive an attack or two.

So if they wanted to go to war in full force, even all the servants would be joining, apart from a few to keep guard of the tomb so it's not left entirely undefended. Like I said, if Sanguine and Oliver wanted they could go to war with all three countries at the same time and win in a matter of days. xD But that wouldn't be fun, imo...the rp would be over way too quickly that way. And the rp is more about their actions/reactions than fighting, even if there will be plenty of fighting to be done.