Harry became Winter Knight and is allied with Mab as a result. If he had taken up a Coin he'd have been allied with Nicodemus (WoJ). If he'd gone full necromancer would he have been working with Cowl?
The first two power up's have him working with unsavory people that like it or not he has to work with. So if he'd gone Necromancer it would have been the only one without some kind of alliance. That is unless Cowl was that unsavory person he'd have to work with. The biggest deal about this is that Cowl is an unknown while Mab, and Nicodemus are not. Also Cowl appears to be working with Nemesis. So that doesn't seem likely for Harry to team up with him....
What do you think if he'd gone Necromancer? Who'd he work with if anyone? If Cowl does that mean Cowl is either not as bad as he appears or that Mab, Nicodemus, and Cowl are different sides of the same evil Coin?