Anodized Resistors increase your Energy and Projectile resistance, enabling your ships to fight effectively at all ranges, against both Striker and Outpost targets.
Hybrid resistors are much more mass efficient than individually equipping two basic resistors. They also have no repair time and actually increase the repair efficiency of your cruisers as the added resistance effectively grants extra armor.
Hybrid resistors lack Alien resistance; be wary of advanced Xeno/Alien weaponry!
The definition of "anodize" is to coat (a metal, especially aluminium) with a protective oxide layer by an electrolytic process in which the metal forms the anode, which explains its name.
It was originally intended to cost 4%/7%/10% ship mass.