Unfortunately I cannot disclose any specific numbers for the enhancement rate. However, the success will naturally go down the higher the Tier and the higher the Enhancement of the weapon.
Base on feedback, we can always review success rate.
Then can you please comment on if Gamigo has implemented/plans to impliment/has talked about the addition of a system that increases the chance of a success after each failure? Short of increasing the rates, bracelets seem to be the perfect items to test a system like this...and this tread plus MrRadian's video will probably discourage a lot of players from trying.