(Editions of PP in the US conform to US spelling - so the "u" is missing from how Bunyan spelled "armour." This is actually not so easy to render in an edition. Seventeenth-century printing and publication have no fixed spelling norms, and PP has the same word spelled in different ways within the text. There are also conjugations of verbs, "durst" (dared) and plain grammatical mismatches of plural persons and singular verbs, e.g. they was, etc...)
But Christian is not just missing a "u" in his armor. But what he is missing is a result of Bunyan's reading being different to ours. This has to do with translation. Translation, that is, of the Bible.
Famously, Christian realizes that he cannot turn his back to flee Apollyon in the Valley of Humiliation. This might be surprising, as, when wanting to set out from the Palace Beautiful,
he is told, '"Let us go again into the Armory." So they did, and when they came there, they harnessed him from head to foot, with what was of proof, lest perhaps he should meet with assaults in the way.' Isn't it odd then that he is apparently unprepared for combat by having literally half of his armor missing! But of course, Christian's armor is furnished not from the military hardware specialists but from the Bible.
In an earlier tour of the Palace, Christian is guided 'into the Armory, where they showed him all manner of furniture [equipment], which their Lord had provided for pilgrims, as sword, shield, helmet, breastplate, All-Prayer, and shoes that would not wear out. And there was here enough of this to harness out as many men, for the service of their Lord, as there be stars in the heaven for multitude.' So there's loads of this armor, but still no back plate protection? That's because the quartermaster got the inventory from Ephesians 6, where you may be accustomed by modern translations to read something like:
Put on the full armor of God, so that you can take your stand against the devil’s schemes. 12 For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms. 13 Therefore put on the full armor of God, so that when the day of evil comes, you may be able to stand your ground, and after you have done everything, to stand. 14 Stand firm then, with the belt of truth buckled around your waist, with the breastplate of righteousness in place, 15 and with your feet fitted with the readiness that comes from the gospel of peace. 16 In addition to all this, take up the shield of faith, with which you can extinguish all the flaming arrows of the evil one. 17 Take the helmet of salvation and the sword of the Spirit, which is the word of God. 18 And pray in the Spirit on all occasions with all kinds of prayers and requests. With this in mind, be alert and always keep on praying for all the Lord’s people. (NIV)
Here's a quick drawing I suspect I did back in 2005 at an IFES InterAction Teams De-briefing Conference in Barcelona. Around the figural representation of the Armor of God I have a number of prayers that I was blessed to pray again today in writing this post. It's all there in terms of armor...
But Bunyan cheats - he gives Christian sandals that will not wear out by borrowing from Deuteronomy 29:5, 5 Yet the Lord says, “During the forty years that I led you through the wilderness, your clothes did not wear out, nor did the sandals on your feet.' NIV Or, as the KJV has it, '5 And I have led you forty years in the wilderness: your clothes are not waxen old upon you, and thy shoe is not waxen old upon thy foot.' (Proof that Bunyan's 17th century English, using wear rather than waxen, is easier than the KJV)
And Bunyan also seems to neglect the truth! Or rather, he doesn't give Christian his belt, and seems to omit it from the Armor altogether. Why so? It seems unlikely that he opposes truth. Well, the simple answer is that Bunyan's Armor comes from the English translation of the Bible available to him. The KJV has, instead of belt of truth, the following, 'Stand therefore, having your loins girt about with truth, and having on the breastplate of righteousness, etc. So truth as an abstract noun is part of the deal but there is no concrete noun for belt, instead we have the verbal phrase 'girt about with'. So Bunyan didn't have a belt to give Christian, just as, of course, he didn't have a back plate in the armor, but only a breastplate (and it's a great plot device too!)
And lastly, the added secret weapon? Well, it's in his Palace Beautiful armory, but not in our modern translations of Ephesians 6. Christian, after defeating Apollyon with the sword, ventures through the Valley of the Shadow of Death. He realizes that the foes he faces here cannot be defeated by physical assault - so he sets aside his sword and take up....All-Prayer!
Where modern translations have, 'And pray in the Spirit on all occasions with all kinds of prayers and requests' the KJV has 'praying always with all prayer and supplication in the Spirit.' So Bunyan gives Christian the added secret weapon of All-Prayer!