I have to admit, I rather like the possiblility to get some stuff early on for mages.
Sure, 3% might not mean much (and say +10% = 0.1 point of dmg for my flaming sword), but if I'm using a hero that will become a mage, thats still a better option most of the time than say, picking +20 weight capacity on level 2-4.
So I can see ManiiNames point that it's quite useless for non-mages, but then again alot of the "physical" level-up bonuses the game has is quite useless for mages - imho tahts why you get 5 picks at level up - if you find 2 or 3 "for your class" you can still choose the one that you like most.
Firestarter nets -1% Synergy per level to earth shards, but it seems that air synergy is just -0.1% / level. At least in my latest game my level 20 sovereign gets -20 Earth and just -2 Air synergy.
Also there seems to be a technical restriction with the spell that transforms a Shard to an XXX Shard (say, Fire): If you have a Water/Air/Earth altar there you can't transofrm the underlying shard. I guess b/c it's technically not a "Shard" anymore, but an "Altar" now ?
Not sure if that's WaI, so I'll just mention it, I guess