njvack wrote:+1 to replacing them all with !haste — duvessa is right; it has a lot of the same function as the other potions ("be better at doing what you want to do") with the added bonus of being mechanically clear.
It's not functionally the same as haste though, a flat 1-10 bonus to attack damage from might has a relatively small effect on some weapons, and a REALLY large effect on for example, quick blades or daggers. It's possible to use !might to kill an OOF with a quick blade, !haste just lets you do not enough damage faster.
For *many* applications haste is more powerful than !might or !brilliance, although it doesn't really apply to !agil at all (!agil is closer to "lignification, but you can also move") but for some applications, !might/!brill are more useful, the quickblade example above, and for example being able to cast spells you couldn't normally in your current condition (drained/wearing armour/etc) sometimes those spells make a larger difference than the effect of !haste.
So while there are examples where there's a significant overlap, there's also sufficient area where they *don't* overlap that they have a pretty large value in terms of giving you tactical choices.
Flattening the game into "these choices are all kinda sorta close, so let's only make them one choice" makes the game shallower, if the choices *completely* overlap, then yes, you don't lose anything, but if there's areas where they don't overlap, then those areas are valuable choices in terms of game depth.
These !might and !brilliance occupy 2 distinct areas which don't overlap with haste, 1. The general case of "they make you better at doing what you already do" for this application, they are actually *generally a little worse and available earlier and/or more frequently* and 2. The specialized uses where they mechanic of their application makes them better for certain specific purposes.
!agility really doesn't relate to haste at all (I guess you could argue that running away faster is, in the general sense, a better defense than not getting hit, but it's hard for me to even see any "overlap" there)