Silspace is said to be an 11 dimensional space time.

Doctor Halsey's personal journal goes into further details about these beings mathematical.

 Lower dimensional beings are described to not be able to survive in these higher dimensional planes without protection, so surviving these planes without any would scale you with them. This is narratively implied heavily after the Didact survived Slipspace (2:33).

To survive this 11 dimensional space time would scale you to it seeing as lower dimensional beings die from direct exposure to higher planes via the halo verse’s interpretation of dimensionality. This would not only scale his Durability but also his AP seeing as he’d have 11 dimensional axis within his being.

You can’t downscale your own dimensionality passively (unless shown to do such,) so Chief being able to interact with, slightly harm, and even tank a beating from Didact Post events of Halo 4 would scale him to 11 dimensional in terms of not only Durability but Attack potency, seeing as he was able to interact with a being with 11 dimensional axis.

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Possess rifles (in base) capable of harming/staggering this same 11D Being.

This was pre armor adaption amp as well (Master chief only got stunned by Didact by the way.)

So, so far, 11 dimensional scaling.

You can argue since he’d be beyond the standard settings of time and space, he’d possess immeasurable speed as well but it’s more contentious.