Boxed equation with title and subtitle using tcolorbox

Question

I'm looking for a method to improve my current command:

\newcommand{\deq}[2][]{\begin{tcolorbox}[
    colback = blizzardblue!30!white, colframe = white,
    top = -0.3cm, bottom = 0.1cm]\begin{flalign}
        \text{\bfseries #1} && #2 & &
    \end{flalign}\end{tcolorbox}
}

that produces

What I want to improve is to be allowed to write a second title for the equation. Using a table, I get this:

but I couldn't find a way to center horizontally and vertically the equation. The code for the table is this:

\begin{tcolorbox}[
    colback = blizzardblue!30!white, colframe = white]
    \begin{tabularx}{\textwidth}{Lcr}
        \bfseries Clausius's Theorem 
        & $\dps\sideset{_R}{}\oint \frac{\dbar Q}{T} = 0$ & \refstepcounter{equation}(\theequation) \\
        \bfseries Part of the Second Law of Thermodynamics
    \end{tabularx}
\end{tcolorbox}

I'm using this packages:

\usepackage[italicdiff]{physics}
\usepackage[scr = rsfso]{mathalfa} 
\usepackage{mathtools} 
\usepackage{amssymb}
\usepackage{xcolor}
\definecolor{blizzardblue}{rgb}{0.4, 0.6, 0.8}
\usepackage{tcolorbox}
\tcbuselibrary{skins, breakable, hooks, theorems}

The best answer to the question must contain the equation centered (horizontally and vertically) and a command (like the one I wrote) to produce the table/environment with 3 arguments: #1 equation (mandatory) and, if it's possible, #2 primary title (optional) and #3 secundary title (optional). I don't know if this possible to have more than one optional argument. Thanks for reading and for you help!

Answer 1

I'd set the second part outside the flalign.

\documentclass{article}
\usepackage[italicdiff]{physics}
\usepackage[scr = rsfso]{mathalfa} % para \mathscr
\usepackage{mathtools} % si molesta sacar.
\usepackage{amssymb}
\usepackage{xcolor}
\usepackage{tcolorbox}
\tcbuselibrary{skins, breakable, hooks, theorems}
\definecolor{blizzardblue}{rgb}{0.4, 0.6, 0.8}
% https://tex.stackexchange.com/a/282196/4427
\newcommand{\dbar}{{d\mkern-7mu\mathchar'26\mkern-2mu}}
\NewDocumentCommand{\deq}{omo}{%
  \begin{tcolorbox}[
    colback = blizzardblue!30!white,
    colframe = white,
  ]
  \setlength{\abovedisplayskip}{0pt}
  \begin{flalign}
    \IfValueT{#1}{\textbf{#1}} && #2 &&
  \end{flalign}
  \IfValueT{#3}{\bfseries #3}
  \end{tcolorbox}
}
\begin{document}
\deq[Clausius's Theorem]
  {\sideset{_R}{}\oint \frac{\dbar Q}{T} = 0}
\deq[Clausius's Theorem]
  {\sideset{_R}{}\oint \frac{\dbar Q}{T} = 0}
  [Part of the Second Law of Thermodynamics]
\end{document}