First, this is not about one-handed vs two-handed. I don't particularly see much point in wanting two-handed implements to be viable, and making them viable without introducing major balance problems would be very tricky and involved.
This is all about accommodating the various types of spells in the game.
Type 1: Straight damage
For simple pure damage spells, you want spell power, spell focus, and lore. Which is exactly what Thunder-Forged already has.
Great. Perfect. Keep it that way.
Type 2: Healing
For healing spells, you want spell power and lore just like for damage, but focus is useless. Some sort of additional bonus is needed in place of focus. Oh look, Dragon's Blessing.
Dragon's Blessing is along the right lines for a tier 2 healing implement ability, but I'm rather skeptical about it being powerful enough. 100 healing is significant, especially with it being AOE, but the proc rate is too low. 5% proc rate is fine on attack-based abilities - people routinely attack 20 times in 10 seconds or less, making it proc all the time. People do not, however, typically spam heal spells at anywhere near that rate, and healing in general values consistency a great deal more than most attacks do. Even ignoring reliability and consistency, an additional 5 points of healing on average per cast is rather low for level 26+.
The proc chance for Dragon's Blessing should be increased a lot, even if the amount per proc has to be reduced to compensate. In fact, I would go so far as to make it always proc, like the Lantern Ring's Radiant Glory. I would suggest also making it affected by healing spell power and crit chance.
Type 3: Crowd Control
For debuffs, save-or-X, all the spells that have spell resistance, the things you want are spell focus and spell penetration. Spell power and lore are meaningless for these spells, as either there is no damage to be affected at all, or the damage is a small extra rather than the reason to cast it. This is where Thunder-Forged implements fail. Hard. Not only do two of the tiers have nothing useful, but the one tier that is useful forces you to choose only one of the two things you'd want. Yes, you can farm up two implements and use them both, but a) that requires farming up two implements, b) you'll have to pick some abilities that aren't relevant to the implements' primary purpose, and c) that conflicts with the Libram of Silver Magic.
Spell focus is good where it is, we don't want to screw up the damage spell trinity. Spell penetration, however, should be moved to tier 1 or 3. For whichever tier doesn't get spell pen, I would suggest either Wyrmic Minor Focus (yes, taking it away from two-handers, they're not viable for casters anyway), or a proc effect similar to Dragon's Blessing but with a debuff.
Type 4: Buffs
For buff spells, you want, er... Efficient Extend, maybe? Friend-targeted procs? Gear that improves buff spells has always been a thoroughly neglected part of the game, and Thunder-Forged is no exception. I don't really consider this a serious problem, though, as buff spells by their nature are merely a prelude to the main event. When it comes time to actually kill enemies, offensive spells or weapon attacks are required.
If changes along these lines are implemented, there needs to be a way for people who already made their implements to get them updated in a manner of their choice. To this end, Thunder-Forged items with an implement bonus that were upgraded to at least tier 1 before such an update should be deconstructable back into the full original ingredients required to make and upgrade them.