To gain the armor I have to roll an Intelligence arcane of 4
A good thing to realize is that when a card gives multiple options to defeat or acquire, you simply pick one and go with it. So, in this case, the card says "Check to Acquire: Intelligence Arcane 4." This simply means the check to acquire is EITHER Intelligence 4 OR Arcane 4. All you have to do is pick one. If you pick intelligence, then roll whatever your card says for intelligence. If you pick Arcane, then roll whatever your card says for Arcane. It matters not at all whether these two skills are related for your character. In other words, the card is not asking you to attempt an Intelligence/Arcane check, it is asking you EITHER to attempt an Intelligence check OR to attempt an Arcane check (you decide).