Giles does go behind Buffy's back to attempt to kill Spike - that is getting pretty dark. I think that decision was rooted in his earler murder of Ben. Ben wasn't killed for what he had done but for the fear s/he might do more. Pre-emptive murder is pretty dark.

And to lecture Buffy on being a general while at the same time taking her power to lead away from her seems - at best not well thought out.

Worst of all, he and Wood are stupid enough to collude in attempting to do exactly what the First wants them to do.