So, your great grandfather was a Skipper in the Royal Naval Reserve (RNR). This most likely means that he was captain of a fishing vessel brought into service for the war. However, this is by no means certain - Skipper was a rank equivalent to Warrant Officer in the regular Royal Navy, and so RNR Skippers could serve in other positions. Contemporary Navy Lists give two Skipper H Howards RNR serving in the service: Harry Edward Howard, who received the rank on the 26th Jan 1915, and Harry Howard, with seniority from 7th April 1915. Beyond that, there's not that much information on their service available online.

The requirements to become a Skipper RNR are given here:

To qualify for the Warrant Rank of Skipper, Royal Naval Reserve, a candidate, other than a Second hand, must:— (a) Have commanded a British steam trawler for at least two years, and have served at sea in this capacity within six months of making application for appointment. (b) Possess a Board of Trade Certificate as Skipper (c) Have satisfactorily completed the qualifying period of training prescribed in Para. 32 A.

The qualifying period was just 8 days of training aboard a trawler, with 4-8 days of additional training every two years.

From the remainder of the inscription, the R.W.F is most likely the Royal Welsh Fusiliers (from 1920, the Royal Welch Fusiliers), a Welsh infantry regiment. Several battalions of this regiment served in Egypt, but the one that is relevant is the 2nd Garrison Battalion. This served at Cairo from April 1916, but moved to Sollum in 1917, where it would remain until after the signing of the Armistice. The cigarette case was presented by the senior non-commissioned officers of the battalion, the sergeants and warrant officers. A number of trawlers, both hired and those constructed for the Admiralty, served in and around the Gulf of Sollum during the war, with one, Fulmar, being mined in January 1916. Another flotilla served around Alexandria, losing two ships over the course of the war. They had several duties, primarily ASW patrols and minesweeping.

Hello there! As your question is related to looking for identification/information regarding military personnel, our Guide on Military Identification may be of use to you. It provides a number of different resources, including how to request service records from a number of national agencies around the world, as well as graphical aids to assist in deciphering rank, unit, and other forms of badges or insignia. While the users here may still be able to lend you more assistance, hopefully this will provide a good place to start!