Tower CIC described an unsafe situation when observing a newly certified controller who was having extreme difficulties formulating control instructions; appearing to be flustered.

Narrative

I was assigned CIC for the day watch. I was relieved from the RADAR sector by a low time controller who had been on vacation for over 2 weeks and only back to work for 3 days. The Controller indicated they might want help; so after a brief biological break; I came back and plugged in to assist. The Controller had created a complex traffic situation involving two other aircraft; of which one did not acquire a Data Block. I was assisting the Controller with vectoring a Dash 8 to the localizer from the west and did not notice the C182 less than 3 miles east of the final. The Dash 8 was descending from 5;000 to 3;000 cleared for the ILS Runway 16R; while the C182 was level on the opposite downwind at 4;000; but inside 3 miles from the final. I told the Controller to turn the C182 to a heading of 030 for traffic; the Controller gave the instruction; but the pilot read back heading 360. The Controller reiterated the 030 heading; but did not emphasize 'immediately' or call traffic. Leading factors; in my opinion; the Controller did not take the hand off on the Dash 8 from the Center in a timely manner; thus creating a difficult situation in vectoring the aircraft to final. Additionally; the Controller released an aircraft from a satellite airport to do practice approaches at a major airport a bad time and without appropriate positive control. The Controller didn't recognize the limited Data Block and effectively control the aircraft; therefore becoming an eminent situation with another IFR aircraft head on at 4;000. This created a distraction for me; as I had to give additional instruction to the Controller to get them to react to that situation. Additionally; I was responsible for the operation and had to answer the telephone while assisting the Controller. I informed the Controller that they might have had a deal. The Controller appeared very flustered and was having difficulty formulating control instructions. I immediately saw the distress and relieved the Controller. Recommendation; next time I'll work it myself. This Controller was certified right before going on an extended vacation; which in my opinion; might not have been appropriate.