There's a famous statement of Ali ibn Abi Talib which is quoted in sahih al-bukhari but not translated by the translator on sunnah.com as he quotes the hadith confirming it without quoting the content.
وَقَالَ عَلِيٌّ حَدِّثُوا النَّاسَ، بِمَا يَعْرِفُونَ، أَتُحِبُّونَ أَنْ يُكَذَّبَ، اللَّهُ وَرَسُولُهُ
This statement was explained by a contemporary scholar as follows:
Shaykh Muhammad ibn Saalih al-‘Uthaymeen (may Allaah have mercy on him) said, explaining the words of 'Ali ibn Abi Taalib, “Talk to the people about what they appreciate and accept; do you want them to reject Allaah and His Messenger?’ (narrated by al-Bukhaari) as follows:
The words in the report of ‘Ali (may Allah be pleased with him), “Talk to the people” means when preaching and otherwise. “What they appreciate and accept” means, what they may understand, so that they will not be confused. Hence it was narrated that Ibn Mas’ood (may Allah be pleased with him) said: “You will never tell a people anything that they do not understand but it will be a cause of confusion for some of them.” Narrated by al-Bukhaari. (source)
The Quran also teaches us when we explain or teach something to take care of those people we are addressing read for example the verses:
... And speak to people good ... (2:83)
Invite to the way of your Lord with wisdom and good instruction, and argue with them in a way that is best. ... (16:125)
And tell My servants to say that which is best. ... (17:53)
What I want to say with this is that our Prophet (pbuh) here might have applied this and told people about the day of resurrection in a way they understand.
Note that we still have swords nowadays and also note that we don't know what kind of weapons would be present at that time so anything is possible, a return of swords, swords can be put here as a synonym of guns etc. or they may refer to any weapons that would be existing at that time.
On the whole the statements of such ahadith are somewhat vague.
For example if قُسْطُنْطِينِيَّةَ really refers to Constantinople/Istambul than the hadith would suggest that this city was conquered again by the Rum (the Christians/Bizantines). Therefore some commentators say that a first conquering happened at the time of sahaba and the 2nd was the one by the 'Othmans. Also note that the Muslim army will start from Medina as it seems, which doesn't apply for the 'Othmans.