Looking at big weapons there is 3 things i can think of. Big DMG, multiple target and Slower Atk speed. Those traits are usually applied to this type of weapon in most games.
Looking at D&D 3.5 the first version that inspired ddo( but not the only) the atk speed factor was never clearly managed there or here in DDO. We actually have mechanics in place to remedy for 2wf(offhand chance of atks) and SwF ( extra atk speed).
Also looking at the planned changes in the 2hf I feel its fair to try to balance things out but sad to loose its big DMG part. Such instinctive and inconic aspect of 2hf weapons.
For this my suggestion is actually to create 2 2hf stances.
Warmaster combat stance: Players can choose to keep their striketrought and use the new 2hf mod multipliers for dmg while using a 2hf weapon.
Executioner stance: Players can sacrifice their striketrought chance to focus on only one target . That way they can keep the 3x stat mod for dmg( or higher if you dont mind =p ). -5% atk speed and 5% longer Cooldown for melee actives atacks.
Switching stances would take time and have CD like Epic Defensive Fighting have. Extra penalty or buff to each stance or stance changing would be open to discuss by witchever dev implementing it.
Just tossing the raw idea. Having the big numbers we have now without any drawbacks seems to be not of interest but loosing this part of its fantasy or just loosing striketrought dosent look good too. So thats is my other way suggestion .
All this could be a new class concept but i feel like its fair to have it acessible to any 2hf character.