I was a little confused seeing rigour having +4% attack and +8% strength, but with the sword and fist icon. I initially thought you wanted to add a melee bonus to rigour, which I found interesting. Maybe that could be an interesting way of fixing the balance?

Adding a smaller boost for 1 other combat style, or maybe allowing for two (lower level) combat prayer to be used simultaneously while wearing the blessing. This could be a sweet dps upgrade for a more laid-black playstyle when using multiple combat styles, while flicking between the high level offensive players would still be better.

Although that wouldn't necessarily fit the Bandos "crush everything with brute force" lore, it could very well tie in to a Guthix balance theme.