BRATISLAVA, Slovakia — The European Central Bank cut its benchmark interest rate to a record low on Thursday. But its president, Mario Draghi, indicated that his promise last year to do “whatever it takes” to save the euro had limits.

For now, at least, the bank remains unwilling or unable to wield the more powerful weapons that many economists say are needed to jolt the Continent out of recession. Although the big fear last year that the euro zone might break apart has receded, the danger now could be prolonged stagnation like that which has plagued Japan for most of the last two decades.

Even the traditionally conservative Bank of Japan has become bolder lately, aggressively buying government bonds to try to double the supply of money in circulation and spur growth. Such a step would be unthinkable for Mr. Draghi, who is hemmed in by the bank’s narrower mandate and the historically rooted inflation fears of Germany, the euro zone’s wealthiest and most politically powerful member.

The bank’s Governing Council, meeting in Bratislava, reduced its benchmark interest rate to 0.5 percent from 0.75 percent. But that move was widely seen as mostly symbolic, to avoid the impression that the bank and Mr. Draghi were doing nothing as the euro zone recession threatens to engulf countries, like Germany, that have previously been spared.