I think you may be putting too much significance on the semantics of some mnemonics that are perhaps phrased more absolutely than they are intended to be used. That is particularly true with the phrase that "water is the universal solvent", which is not really a scientifically significant statement at all. Certainly gasoline, or mineral oil, will not dissolve in water, even in very small quantities, so why would it be considered "universal" in the sense you seem to be taking it?
To answer your question, the better rule of thumb is to use the statement that the solvent is always the component present in larger quantity .. but even that is not correct in all cases. For example in a multiphase extraction, there can be multiple solvents ... components that are polar will dissolve in the aqueous phase, so for those components, water is the solvent .. while components that are non-polar will dissolve in the non-aqueous phase, which will be the solvent for those components.
A final point is that for something like a 49-51% mixture of ethanol and water, the concept of a solvent becomes largely academic ... is the ethanol dissolved in the water, or is the water dissolved in the ethanol? The answer is: both, and neither .. they are miscible liquids, so it's a two component mixture, rather than a solution. The physical properties of a mixture depend rather strongly on the properties of both components, while the physical properties of a solution are more likely to be dominated by the properties of the solvent.