User blog comment:The Awesome X!/Why don't the monsters use mortal weapons?/@comment-3146930-20131112231607/@comment-7492541-20131113001755

^ "Because monsters, Titans, and gods are immortal, they have no concept of the future and are not meant to change."

So why Apollo uses Ipod? Because Hermes know how to drive and worry about getting into double row? And because they speak English? And besides, Ares does not carry grenades and bazookas?... Actually on Lost Hero, says that the gods are influenced by the current culture.

But I think what you said is actually refers to the main character of the gods. Artemis always will love hunting, Apollo will always love music and so on ...And the Titans were enemies of the demigods is almost an absolute standard that would be difficult to change.

Responding to the OP, is the same reason that the demigods do not use guns. The ammunition would be limited, while a sword can be reused.