the way this rhymes i thought this ought to be some sort of saying or song, and there is a song about it haha :D
i did not even look--but version 2.0 will have "zbraně", and then the What the?! skill can get the direct quote :-) BTW, from time to time, please drop by to let us know if a gem of a sentence/word begs to be added, like here!
This has been asked quite a few times before, like https://forum.duolingo.com/comment/25071408/I-do-not-know-whether-to-look
If you search you will find more.
Vím is the first person singular form, while nevědí is the irregular third person plural form for the verb vědět. See, for example: https://en.wiktionary.org/wiki/v%C4%9Bd%C4%9Bt#Conjugation, for the full conjugation. (Click on Show if the table doesn't immediately appear.)