Philip I AR Antoninianus. 248 AD. IMP PHILIPPVS AVG, radiate, draped & cuirassed bust right / P M TR P V COS II P P, Mars standing left, holding branch & resting hand on shield, A in left field. RSC 145.
Nice coin. Could be that he was looking for an end to war whcih was hitting Philip from all sides, one reason why he became unpopular is that he chose to pay off enemies rather than fight...this could be peace being offered to enemies? assuming it is an olive branch. Dont know.
Here is an example I have:

A.D. 244-249 (IMP) Philip I (the Arab) – AR / Antoninianus / RIC 38b/ Sear 2561 / IMP M IVL PILIPPVS AVG / Radiate draped bust right / LIBERALITAS AVGG II / Liberalitas standing left with abacus and cornucopiae / Rome Mint
real quick bio of this General / Emperor:
http://www.cachecoins.org/philipthearab.htm