I can actually try to do it but the tricky part is as you said, it's pretty hard to determine exactly how powerful he is. Before the existence of TAS and DMC4, Dante was considered a lot weaker than today.
Also determining how strong is Mundus, how strong was Sparda and how strong Dante gets with Sparda sword are also pretty impossible to determine. There are just too many unknowns going on.
if you have the time and resources please make one, just do with the closest one describing dante's strength justice, pretty sure other members will gladly contribute to the thread.. and this is a devil may cry forum, i think we need that..
the only DMC that made me feel dante is strong is DMC3 even if he was supposed to be the weakest there, like
@Foxtrot94 said, we see vergil doing stuffs, and i see jester making fun of dante in the cutscenes, and dante beats them.. and the vergil fight was really hard for me, hurts my fingers, backthen at least.. least the game clearly shown dante is strong eventho he takes thing lightly..
and reading stuffs about how strong enemies are don't do justice to dante's strength.. i finished 1, 3, 4 and DmC, i guess skip DmC, the game seriously don't do justice strength wise.. my memories aren't so good about 1, but i don't think mundus is as the description when fought, and in 4, they're the same bosses and nero could handle them, cept for that one part since he's too focused on kyrie..