I already posted this question in response to the Valeros strategy blog post but I realize that there is probably more chance that I will get an answer if I post it there instead, so there it is :
If I am reading the rules correctly, Valeros Drunken avenger role is risky, as proficiency with liquids give you a roll for recharge during recovery (that Valeors will usually get to do with a base 1d4 for not having the craft skill plus the 1d12 bonus) but doesn't prevent the liquid boons from being banished if you fail the recharge roll (and at 2 dice without any static bonus, it will happen).
This also mean that the power feat to recharge a liquid boon from your discard is almost useless, outside discarding for damage or similar, your liquid boons when used will eitheir recharge or be banished.
Did I miss something ?
I haven't played with Valeros yet, but well, proficiency with Liquids seems only like a tiny bit of upgrade for power feat. Before that, he would just banish those liquids, now he has a small chance of recharging them during recovery. Don´t forget there are many ways how Valeros can give himself bonus with Craft as well.
As to the power that allows him to recharge from discards, it's almost as you said - there are only few ways how liquids end up in his discards, damage being one of them. However, there is a small bit you missed. The ability is worded "hand or discards". Sometimes it might be useful to just get that potion you really don't need on the bottom of your deck instead of just throwing it in your discards and hope to draw a better card during reset. Just one side comment - armors also do not often end up in your discards ;) as they generally recharge or bury, with many exceptions of course.
This power may bloom in the future with more liquids - unless you think about older decks and conversion guide...
Thank you for the answer. Good point about the "recharge from hand" part, still not very useful but better than nothing.
I have just started playing with Valeros in a new CotCT campaign, I suppose that I will probably end up with the other role, recharging allies from the discard should be much more useful and fighter types often have a hard time exploring multiple time, this should help a lot.