"In One Piece 15th Anniversary: Dive to Grand World(Scan 3), it states:
”海賊達を取り締まる、 歴戦の 強者! 元帥、大将、 中将・・・と階級が存在する。 上位であるほど戦闘能力とカリスマ性を 併せ持っているのだ。”
Translation: The powerful men who have fought many battles to control pirates in the past! There are various ranks: Fleet Admiral, Admiral, Vice Admiral, and so on. The higher the rank, the greater the charisma and combat ability."
And although it's in a panel that contains an outlier, we see him use visibily black Armament on his entire sword here:
He could also match Zoro, Luffy, and Sabo's Armament Haki. All of which scale to.. About 3-4 layers? Well, we know Zoro clapped Pica's full body Armament and Luffy's Armament > Doffy's Armament ~ Law's Armament > Vergo's Armament.
In terms of Observation, his is very good.
He can precisely drop rubble on only the enemy fleets, with none of it hitting the Grand Fleet or Thousand Sunny.
He can also find and drop meteors all the way from space to hit opponents.
He also matched a kick from Sabo, who used his DF, while a basic kick from Sabo had damaged Burgess and knocked him away.
Which is impressive, considering Sabo's kick did about as much damage to a stronger version of Burgess than Sengoku's shockwave did to a weaker version.