Limit Breaks are one of the areas that FFXIV can greatly improve.
Here is what I think they could do:
1 – First, the hardest part (probably only in a future expansion) – give each Job their own unique Limit Breaks.
1.1 – DPS Jobs would get a ST and an AoE Limit Break for the same level at 1 or 2 different levels, which might vary from Job to Job.
So BLMs might get ST+AoE at levels 1 and 3, and DRG at 1 and 2, etc.
2 – At level 15, you unlock your own Limit Break Gauge, but can only reach Level 1.
3 – Once you obtain a Job, your own Limit Break Gauge can reach Level 2.
4 – Your Limit Break action is replaced with Limit Break I, Limit Break II and Limit Break III.
So you can control what strength of Limit Break you want to use at any time.
5 – Duty Gauge is not removed. When you attempt to use a Limit Break, you use up your Limit Break Gauge first, and if you need more, then use any missing Gauge from your Duty Gauge.
6 – Since your personal Limit Break Gauge only goes up to level 3, the only way to use a Limit Break Lv3 is in a Duty, using up both your Gauge and the Duty Gauge.
So if you have Level 2 Gauge filled up, and Level 2 Duty Gauge filled up, and try to use a Limit Break III, it uses all your Gauge plus 1 Level from the Duty Gauge.
1 – Encounters might need to be adjusted to reflect this “buff” (increased boss HP, etc).
2 – Limit Breaks might also need to be weakened due to their more frequent availability, and in order to prevent them from being too strong if available in PvP.