Katana and scoped kar 98 bayoneted, simple, effective, easy to use and extremely satisfying. Kar 98 is a WW2 German bolt action rifle and is rugged, easy to clean and excellent in close combat. The Katana i hope you know is a Japanese samurai sword. The Kar 98 is not completely useless when you run out of ammo as is nearly all modern rifles.
I would be carrying
My trusty H&K (MP5) 9mm
Benelli (M4 tactical shotgun) 12 gauge
Glock (34 semi-auto) 9x19 cal.
Colt Python (357 mag.
Emerson (XL) machete
My home made special (Trench Spike) with brass knuckles ;)
No seriously though, I'm looking at dual sledge hand mallets, heavy enough to cave in a skull but not too heavy as to be cumbersome or overly tiring too quickly. Most likely a Sig 220 p auto with a few spare magazine, moderat sized and powerful. And if I was lucky enough to find one then maybe an automatic shotgun for those tight packed in moments with a spray painters mask for blood spray protection. All in all something for most scenarios without over encumbering myself and allowing for efficient lethality without the cons over shadowing the pros.