You have to have a little patience with this movie, sort of like with the first season of ST:TNG. It gets a little better as it goes along, and the actors get used to each other and their roles. Franco Columbo looks great, for someone who's 60 (or even someone who's 40), but he's totally unbelievable running around with a couple of pistols. He doesn't seem to know just what to do with them. It's better when he's carrying a machine pistol, but he's "The World's Strongest Bodybuilder", not a martial artist or action hero. His performance varies from pretty good to less than average. He's more believable in the non-combat scenes.
Supporting cast is good, performance more even, overall better than average, but the script and plot are both a little weak. The dialog, and the action scenes, are mostly ordinary and unimaginative. You've seen it all before, but better.
If you're considering this movie because of a "supernatural battle against the ultimate evil" blurb (from the DVD I watched), you're going to be disappointed. Whoever wrote that has more imagination than the scriptwriters, and probably never saw the movie. Don't expect much from the 'Ancient Warriors' of the title. They seem more of an afterthought, and play a very minor role in the movie.
There's some entertainment value here, but, like I said, you'll have to be patient and let it dribble out.