In the juggling around to get some variety in the 2HB weapons, an accidental duplication of stats happened. Rather than mess up anyone who already has one of these weapons, the sledgehammer recipes will be retired with the next GU, to be replaced with a sledge recipe. Domino provides a bit more detail in this post in the SOE forums
It seems that somehow the sledgehammer and war mace ended up with the exact same stats (str/sta/int, 2h crushing, 6 delay). Since a bit more diversity would be welcome, and since a str/wis 2h crushing weapon seemed to be lacking, the sledgehammer recipe is going to be removed from weaponsmith recipe books with GU46 and will be replaced instead with a "sledge" recipe that will make a str/wis 2h crushing 6 delay weapon (with the same graphic the sledgehammer had).
Any sledgehammers already out there in the world will remain unchanged, they just won't be craftable any more; folks who want those stats can get the war mace.
Just an FYI for y'all, and as usual, these changes will be showing up on Test when it's updated with the GU46 stuff, so feel free to head on over and check out the details!