If you are in a situation when you are about to encounter a heavily armored opponent (not general likelihood, but exact knowledge that the enemy is somewhere nearby), why would you not take a píšťala or hákovnice with you, even if it was one shot only? (Or crossbow for that matter) That would not preclude you from wielding the sword thereafter.
Also, being prepared to defend oneself from anticipated attack by having a loaded firearm was not a murder in 1403 as same as it is not a murder today, at least in the Czech Republic (see, for example, decision of the Supreme Court of the Czech Republic (17 February 1981), Decision No. 3 To 2/1981, or http://en.wikipedia.org/wiki/Gun_politics_in_the_Czech_Republic#Self_defense_with_firearms)