Platinum Games and Square Enix have let the word out to expect a crossover between both games that will allow you to use each game’s weapons in the other.
When Nier: Automata launches at some point next year, expect to find Noctis’ Engine Blade available for use by the protagonist, 2B. This weapon will include a damage counter like the one included in Final Fantasy XV and will change how you evade.
This is a two-way event, so expect to see a similar style included in Final Fantasy XV. We can expect to see Nier at some point in 2017. Final Fantasy XV launches on November 29.