I actually think that Sparda would kind of agree with Palutena on a certain level. I find it hard to explain as you don't actually see Sparda himself personally in any actual cutscenes. Only as an unlockable costume for Dante in the Devil May Cry series (the Sparda costumes make him look EXACTLY like Sparda does. Complete with a altered Devil Trigger to look like Sparda's demon form, as well as altered attacks and new attacks in Devil Trigger. In fact in DMC 3 with Sparda's costume Dante's sword is replaced with the Force Edge (Sparda's Sword.))
I also don't think that Sparda would be too upset. Yes he might show some hostility towards Isaac, but after hearing of his feats he would be somewhat impressed.
Also I haven't explicitly stated Sparda's powers and skills have I?
The exact extent of Sparda's powers remains unknown; but it is shown that his powers surpassed even the "Prince of Darkness" himself, evidenced when Sparda single-handedly defeated Mundus and his demonic armies. Though it is to be seen that his powers stem from a heat related aspect, the exact nature of his powers are uncertain as his true form appears to be partly corporeal-scales and flesh-and partly ghostly-as if made from smoke or shadow. As in Dante the abilities and utilization of fire and electricity seem to be among his abilities.Arkham himself likened obtaining Sparda's power to becoming a god. In Devil May Cry 3, Dante was unable to defeat Arkham, who wielded the Sparda sword (and thus Sparda's powers) at the time, until Vergil shows up. However, it should be noted that Griffon in the first Devil May Cry stated, after being defeated for the final time, that "[Dante's] are definitely the powers of Sparda. No, even more so.". Also, Nero was able to defeat Sanctus, who wielded Sparda and was connected to the powers of The Savior. It is suggested in Devil May Cry 4 that Sparda acquired the true extent of his power by embracing humanity, which would explain why the demons who attempt to augment their own power with Sparda's are unable to defeat the Sons of Sparda. He was also implied to be a powerful master swordsman, as he trained Baul and Modeus into powerful swordsmen and Modeus stated that Sparda was "the best swordsman in the Demon World", although Dante went so far as to mock his father's swordwork when he faced Baul.
Sparda is known to have used both Yamato and the Sparda (Force Edge). The former he used as a key to lock the Demon World away from the Human World, and he sealed the power of the latter with the Perfect Amulet, turning it into the Force Edge. Also, in Devil May Cry 3: Dante's Awakening, it is stated that Rebellion is a memento from Sparda to Dante, though its exact significance is unknown.
He also used the Luce & Ombra, his own hand made pistols (as shown when you use Sparda's Costume in the Devil May Cry games where Dante's Ebony & Ivory are replaced by Luce & Ombra.)
Sparda in his human form:
Spoiler

Sparda in his demon form (true form):
Spoiler

Force Edge (Sword of Sparda): A powerful two-handed blade containing Sparda's power in the games. When most people wield it they lose most control of it's power and they usually mutate into something dangerous. However there are exceptions.

Luce & Ombra: Handmade by Sparda himself, they are semi-automatic handguns designed to rapidly fire bullets.
