Behold. The Innocent Blade. The Strongest Gear. Man and Machine. Magic and Science and Power beyond understanding. Daijuuji Kurou and Al-Azif. A Magius and his Grimoire. Fei Fong Wong. Son of Man. Reincarnation of Man. Bearer of the Wave.
The Ultimate contest for the ultimate machines.
...and then tea and cakes at the Hadou estate afterwords.
Well Demonbane doesn't start off all that powerful. Story progression makes it a beast. Through Al-Azif and Daijuuji, can use Al's powers (btw that's a girl) and spells and acquired the Tyrant's guns for utilizing the power and summoning two of the "Great Ones" (godlike beings), like Chtugha and Inaqeua (basically fire and ice/wind). Also summon the Scimitar of Barzai and the Mirror of Nitocris, as well as some other nifty stuff, and uses spacial distortions in the leg guards for high-speed movement and maneuverability that breaks the laws of inertia.
The one thing about the story in Demonbane is you discover they have been trapped in an endless timeloop. An Outer God had been recreating timelines and manipulating events to try and bring about a specific result that would free the Outer Gods from the "Original Universe". Basically; "Shit be whack, yo." Anyway, by the end, Daijuuji and Al-Azif enter into the domain of Yog-Sothoth, the One-In-All, the All-in-One, a being that makes Cthulhu look like a child. However they don't fight him, just enter that ream where Euclidean Physics don't apply. However in that place with Demonbane they gain untold power while fighting Therion, the god-born child of Yog-Sothoth, and it's revealed that Demonbane's core draws power from all infinite timelines.
One thing mainly is Demonbane has the Shining Trapozehedron, an object in which the Original Universe is sealed and appears as a dual-bladed weapon that can cut the laws of Fate. Therion also possessed this and it was said when their two blades met, entire universes were born and destroyed from the clash of energies.
All in all, Demonbane is quite powerful. They had even learned to magically regenerate its damaged and lost parts. Also, in case ya didn't notice, the Demonbane series is based off the Cthulhu mythos.