As threatening as Odessa is, one couldn't help but question their competence some times. Just a quick peek at the Cocytus group is enough to make professional terrorist groups at large weep:

First there's Ptolomea, a strong veteran, but too soft-hearted.

Next we have Judecca, a merciless killer, but he toys around with his prey too much.

And then there's Caina, who while powerful, is too inexperienced and dependent on Vinsfield.

And finally we have Antenora, who's... actually surprisingly competent. In fact, her plan of spreading distrust amongst ARMS had almost killed one of their more important members. Oh sure, she's a little crazy in the head regarding love, but she's still brutally effective.

And brutally effective is what she is in battle as well. Ephemeron is able to deal stagerring damage and a wide array of statuses at the same time, making any duelist balk at the thought of facing her. Yes, Antenora may seem insane, but sanity is hardly a requirement for success in the DL Arena, as her Season 23 Middle title and rise to Heavy will attest.