More on the twenty-six secrets.
Comprehensive information about Japanese Tokusatsu Hero - Kamen Rider V3
www.kamenrider.net
A lot of energy absorption and nullification for kinetic and thermal energy, up to and including nuclear energies, adaptive evolution to both techniques and abilities, anything used on him once will not work again, provided that he survives the first encounter with them, electromagnetic absorption and generation, flight, x-ray vision, data analysis of enemies, etc.
In terms of raw strength and durability, you are looking at island level even early on. He survives Destron's island bases blowing up more than once, and I mean completely, there is nothing left of them.
In terms of speed, like I already mentioned, he has reacted to light-based/camera-based explosive attacks and has a secret ability that can hard counter and absorb that, to double his own power output.