(Any advice on which secondary martial art I might take on?)

Well, I study Kali for precisely the reasons you mention, so maybe check out Kali/Eskrima/Arnis, or another SE Asian art like Silat or Kuntao. In Kali we are fond of saying that it is self-offense not self-defense. Instead of blending with our attackers we seek to counter-attack their attack, usually in extremely unfair and dirty ways. The Philippines has a long history of warfare against internal and external threats, and these wars are usually fought by peasants without the luxury of logistical backup. So the mentality is that if you throw a punch at me I'm going to deploy a dagger and cut your arm to ribbons. We spend alot of time on concepts such as "de-fang the snake" and "my target is closer than your target", both of which invlove taking out an opponents hands/arms/feet/legs, often preemptively, and often with weapons. There are other arts that have a similar philosophy/training structure, you might try Krav Maga, Kyokushin, or Boxing- especially if you can find a gym that is willing to teach you "dirty" boxing.

So that's my take on it, but I also do BJJ, which is a 'compliment' to Aikido, the concepts in BJJ and Aikido are nearly identical, but the applications sometimes seen polar opposites. So don't totally dismiss a complimentary approach, since you are newish to MA. I've been doing MA for 20+ years, and it took me more than half that time to settle on my core arts of Aikido, Kali, and BJJ.