I'm at work today and my V8 is abandoning me

Ignition starts when turning the key but in the starter position the engine does not turn.. The X-Relais clicks on the position where the starter normally goes and light switches back, but no starting.
Then, after 50 attempts felt, always turn ignition keys as if starting, only that nothing happens, except that the lamps for oil pressure etc. when trying always a little dimming, then suddenly works nevertheless and the engine starts with normal fast starter speed?!?!
Who's got an idea where I'm most likely to look for the mistake? If the starter were broken, he wouldn't start at all, would he? Or can a relay be broken? Or detonator switch? Who has had this and can say what it can be most likely to be?
Any tip would be helpful! Thanks a lot.
