What is the ruling on saying "luck was against us" or "we need some luck"? And is it considered major shirk? And what is the ruling on saying "internationally prohibited weapons"?

There is no harm in using the word "luck" (الحظ) in the sense of divine preordainment (القَدَر), but any sentence that implies objection to or discontent with divine preordainment must be avoided. As for the phrase "we need a lot of luck," it is better to replace it with "we need Allah's (the Most High) divine grace (توفيق)." There is no objection to the phrase "internationally prohibited weapons."