The true strength of Ethanbaron V. Nusjuro remains hidden, but speculations arise about his formidable abilities.
While Dracule Mihawk is currently acknowledged as the greatest swordsman in the One Piece world, doubts emerge whether Ngũ lão tinh's Ethanbaron V. Nusjuro could surpass him.

Here are some compelling reasons supporting this perspective:
1. Nusjuro's sword is rumored to be the Shodai Kitetsu
For a long time, Nusjuro's sword has been rumored to be the Supreme Demon Sword (Shodai Kitetsu), one of the three cursed Kitetsu swords. If true, it means this sword is one of the 12 Supreme Grade Great Grade Swords (Saijo O Wazamono).

Implying that Nusjuro's sword is on par with Mihawk's Yoru, a renowned black blade.
2. When Mihawk became the greatest swordsman in the world, he likely never clashed with Nusjuro
Mihawk achieved the title of the greatest swordsman by defeating increasingly powerful adversaries. Interestingly, most of Mihawk's defeated opponents are members of the Water Seven, earning him the nickname 'Hunter of Water Seven.'

However, it's possible that Mihawk has never faced off against Nusjuro , as Nusjuro is one of the Ngũ Lão Tinh—five elders holding supreme authority at the World Government. Nusjuro may not have even left Mary Geoise for an extended period.
3. Nusjuro is rumored to have awakened a Zoan-type Devil Fruit
During Sabo's confrontation with the Ngũ Lão Tinh and Im, all of them underwent transformations. This suggests that they are individuals who have consumed Zoan-type Devil Fruits.
In chapter 1094, as Saturn took action, his transformative form exhibited characteristics reminiscent of Lucci's Zoan-type Devil Fruit awakening. If Saturn can awaken a Zoan-type, then other Ngũ Lão Tinh and Im might possess similar abilities.

Now, envision a swordsman in an awakened Zoan form—undoubtedly incredibly powerful.
Considering the distinct Zoan transformation of Ngũ Lão Tinh, Nusjuro might have consumed a mythical Zoan fruit, transforming into a carnivorous beast. Hence, apart from enhanced strength, he might possess other mystical powers.
4. Earns the nickname Godhead
Nusjuro is dubbed the Godhead of Finance. Whether Godhead or Warrior God, Nusjuro 's nickname might stem from more than just being one of the Ngũ Lão Tinh. This character likely poses extreme danger in combat.

This is evident as all Ngũ Lão Tinh and Im seemingly remain unaffected despite Sabo's attacks landing on them.
In chapter 1094, though glimpsed briefly, it's evident that the power of Ngũ lão tinh Saturn is no joke. Nusjuro might share a similar prowess.
5. Tenryuubito without bubble helmets are believed to be exceptionally strong
All Ngũ Lão Tinh are indeed Tenryuubito. However, they don't don the absurd attire and bubble helmets like typical Tenryuubito.

Hence, there's speculation that Tenryuubito without bubble helmets are genuinely formidable.
Take Doflamingo, for example, a former Tenryuubito who, after enduring a harsh life outside Mary Geoise, became one of the strongest warriors in One Piece.