The final chat between Dax and Sisko about Dukat reveals how personal it’s become for Ben. There’s a certain parallel between this and how Eddington’s betrayal hurt him to the core. Eddington and Dukat are two completely different people but there is overlap during their freedom fighter phase. None of that really matters tho because Sisko’s taking it personal, where he’s known Dukat, flown with him, known his crimes from afar, and fought him in military terms. Now it’s down to the two of them as individuals, stripped all the layers and the real Dukat, or this remaining version, is the fight Sisko has to have.