I have been thinking this morning about that indulgentia. The collect in full, in this context from the Office for the Dead, is addressed to Our Lord:
Fidélium, Deus, ómnium Cónditor et Redémptor, animábus famulórum famularúmque tuárum remissiónem cunctórum tríbue peccatórum: ut indulgéntiam, quam semper optavérunt, piis supplicatiónibus consequántur: Qui vivis et regnas cum Deo Patre, in unitáte Spíritus Sancti, Deus, per ómnia sǽcula sæculórum. Amen.
We are entreating the Lord that He grant the dead forgiveness (remissionem) of all their sins, and that our poor prayers might avail for them to receive the forgiveness (here, indulgentiam) for which they have always hoped. Yesterday was the anniversary of the death, in 2007, of a friend who I knew when I lived in Montana.
In post-classical Latin, indulgentia is or can be more or less synonymous with remissio (used earlier in the collect), which is, let us say (am not wanting to turn this into a bad summary of a theology tractatus), a term of art used to describe 'the act of forgiveness'. The proper meaning is 'a yielding, indulgence, forbearance, leniency, mildness, kindness, favour', even tenderness.
Requiem aeternam dona eis, Domine, et lux perpetua luceat eis: requiescant in pace. Ben Spangler, requiescat in pace.
I don't believe I ever went out to listen to the band, and if I did I'm sure I lasted about three minutes-- this is not the sort of music I find listenable. There are several videos at YouTube.