I just thought how they all came off as medieval peasants in silly robes. Or in Prometheus how the alien pilot runs over there... to what... grapple her? No weapons? Come on.
This is actually explained pretty well in the recent Prometheus "making-of" documentary. the Engineers have evolved past the need for violence and therefore don't have a need for weaponry, and they can see multiple dimensions above our own (hence the black eyes), so all their shit is decorated to a ridiculous degree but we can't see any of it.
The problem I have with the first bit is that they explain away the creation of the Xeno by stating that they used synthesized Deacon blood to "seperate" their violent tendencies which led to the creation of "The Beast" aka. the first Xeno. This leads them to the idea of using the Xenos to purge Earth of their failed creation. Yadda yadda, so on and so forth.
The second bit leads to the idea that David can also see higher dimensions, which is why he seems to know everything...he's reading the writing on the wall no one else can see. I hate that notion, but whatever...I didn't make the movie.
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o7 Let strength be granted so the world might be mended.