I have a full chapter on the seizure in my book, The Early History of Gadsden County, which is available on Amazon.com.
I also have a ton of source material on the arsenal and on the Confederate defense efforts along the Apalachicola and Chattahoochee Rivers. If I can help with something you are researching, just let me know.
I have a page on the arsenal on my website at www.exploresouthernhistory.com/arsenal1. It includes some quotes from the available 1861 documentation on the seizure, but if you need more, just let me know.
Best,
Dale Cox