I had a bad experience with Seeking arrow, once I was EA Ulm in a MP game. I was raiding enemy provinces with the stealthy commanders, I got spotted and the next turn I got "Arrow showered" and the next thing I knew was 3-4 dead commanders and several afflicted commanders and not enough of them to keep on leading my armies, they were stuck hiding in the province.
People tell me that if you give commanders shields or items such as the trinket which provides Air Shield. Seeking arrow has a chance to miss or not even affect your commanders at all.