By Balazs Koranyi and Francesco Canepa FRANKFURT/MILAN (Reuters) -The European Central Bank promised fresh support on Wednesday to temper a market rout that has fanned fears of a new debt crisis on the euro area’s southern rim but appears to have disappointed investors looking for bolder steps. Government borrowing costs have soared on the 19-country currency bloc’s periphery since the ECB unveiled plans last Thursday to raise interest rates to tame painfully high inflation that is at risk of becoming entrenched. The sell-off was then exacerbated by the ECB’s vague commitment to limit the rise…