Let me guess... you didn't convert your reference files yourself and downloaded them more than two weeks ago. Hence your reference files are now out of date because the 1.5 patch changed absolutely every single research entity.

Give it a research prerequisite, the Vasari lighter armor tech would have had one. Actually that might also be the problem if you didn't remove that.

And for future reference, in a case like this where you know exactly what file is causing the problem, please put it up on pastebin and link it to us.

Again, for future reference please use either pastebin (no account sign up required) or dropbox, I want to be able to just see the file in my web browser, not download it.

Edit: Well, I guess you can view text files in media fire, who knew.

Well my apologies, yeah it looks like you did that right. There should be an empty line at the very bottom of the entity file, but that shouldn't cause a crash. The next step is to run your mod in the dev.exe and see if it can give you any error messages.