Well, I'd say, that in a downtrend, that hammer is given added significance, because its an indicator of the trend reversing, that's right. But its still just as bullish to see that candlestick. You have to take into account what that candlestick means. It means the stock started at a price below the high of the day. During the day, it retraced for a bit, and towards the end of the day gained some steam and finished at the high of the day.
The candlestick is kind of a self fulfilling prophecy. The stock is moving in the right direction at the end of the trading day, which means it more than likely is going to have momentum into monday, but then additionally, it will have much more attention on monday as people realise that it has a bullish formation. So, in essence, because it is moving, it will pick up more movement. This is the essence of momentum.