I remember that you could check 'how long your knight had been in service' through the Spiral Knights website. Somehow somewhere with the account or something. I know I did it once before, but I forgot how or maybe they removed it. Does anyone know? I'd like to see how old my knight is :)
If you made your account through the web site www.spiralknights.com (as opposed to Steam, Armor Games, etc.), then your wiki-editing privileges were created at the same time. So go to the following URL, enter your user name (not your knight name), and discover.
http://wiki.spiralknights.com/Special:ListUsers