Magic, generally speaking, is an unfair advantage in most games. In FbL too there is no real way to resist magic for non-casters. There are no generic soaking rolls and only sometimes specific ones for each spell. When that blood mage reaches lvl 2 (which can be arranged already at PC creation) they can boil the blood of opponents with impunity.
Yes, and someone with AXE FIGHTER can give people critical injuries with impunity (mostly). Without having to spend WP.
Yes, magic has the potential to be deadly. But every spell require the expenditure of WP, which renders them fairly rare. If your main purpose is to kill your opponents at a distance, you're better off with a bow and arrow.
But if you look at it from a narrative point of view, how likely is it that a sorcerer/druid would risk his own life in order to cast a spell? I certainly wouldn't. With the rules as they are now, it would be like playing russian roulette in order to administer an aspirin (a Druid casting HEALING HANDS or CLEANSE SPIRIT with only 1 WP has a 1 in 6 chance for a mishap).
If you want to cast a spell with more than 1 WP the risk gets even higher, making all spellcasting more or less suicidal. With the rules as they are now I'd never play a druid or sorcerer. Why bother?