Manquant object

Mmph… Mmph. Huh? You want to know where the lock is, so you can go and find it? Mmph… Mmph. Telling you about it is no big deal and I will do so eventually, but there is something you must do for me before I tell you where it is.
I want you to defeat the <HFFFA7272>Arkaros Slave Commanders<HFFFFFFFF> on the <HFFFA7272>Wind Plain<HFFFFFFFF> and use <HFFFA7272>Collecting Skill of Niveau 3 or higher<HFFFFFFFF> to obtain <HFFFA7272>2 Rare Tails<HFFFFFFFF> for me. Nothing too difficult, right?
One of my customers caused a scene complaining that I lost the Rare Tails he left with me. But the thing is that I don't remember receiving them from him. It's baffling. But to maintain my reputation I should endure this sort of thing, right? So please hurry and get them for me. Mmph… Mmph.

Defeat the <HFFFA7272>Arkaros Slave Commanders<HFFFFFFFF> on the <HFFFA7272>Wind Plain<HFFFFFFFF> and use <HFFFA7272>Collecting Skill of Niveau 3 or higher<HFFFFFFFF> to obtain <HFFFA7272>2 Rare Tails<HFFFFFFFF> for me. Mmph… Mmph. Please hurry. My reputation is at stake here.

Hm. Good. You brought it. Now, now. Let's move on to the next order of business.