Well, I finally discovered the source for my confusion. It turns out that if a services administrator (someone added to operserv's admin list) is given access to a channel his access is limited on one side, but totally open on the other. Personally I consider this a little confusing.
So, for example, on #cservice I have limited access. Therefor I can't simply op/deop someone:
[#cservice] /cs op #cservice wlfshmn
-ChanServ!services@nekonet.irc- Access denied.
However, I can change the access list without any problems:
[#cservice] /cs access #cservice add wlfshmn 5
-ChanServ!services@nekonet.irc- wlfshmn added to #cservice access list at level 5.
And this is what caused my confusion.