No problems with some "artistic freedom"
Just make sure you don't use names already in the game. This will not only confuse the players but the game engine as well, if they weren't only very similar but really the same accidently
.
For standard (non-magical) equipment, better go with those items already existant - there are plenty of things to borrow from the original nations and themes. Makes balacing easier as well.
And if you really have to introduce equipment, make sure it sufficiently different from the 'generic' items but still balanced - if this doesn't work, it's obviously too similar to warrant using an item ID for it.
If you're heavily interested in this time period, you might want to try out the 'big' demos of "Gates of Troy", "Spartan" and "Chariots of War" by
Slitherine Strategies Software UK Ltd if you not already know them.