They are fighting in a 500m by 600m Adamantium dome,With a humidity control that will keep Namor fully refreshed,and Wendigo has been shaved so he doesn't smell like wet dog or have his fur weigh him down.
Hmm, tricky one, the urge is to say Wendigo, after all he has fought Sasquatch and Hulk at the same time.
However Sabretooth killed and skinned Wendigo, he was also part of Weapon Prime (although they changed his codename to Yeti in later issues) and he got beat up by Feral.
So he has some really good high end showings then gets nailed by beings who shouldn't really be in his class.
fighting as his (or should that be its) full potential Wendigo should take the majority however Namor's flight and strength, especially when in contact with water would make this one hell of a ruck!
In addition to his own strength and durability (which ain't chopped liver), Namor also has speed, fighting skill and experience. I'm inclined to see him win this.
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Shinier than a speeding bullet.
A non-jobbing Wendigo would destroy Namor. One version Dr.Strange was unsure he could beat, another was taking on Hulk and Captain Marvel w/Rick Jones and winning.