Should be the Valiant Wanderer set but gear I couldn't recall (e/ called Great Hachiryo). You'll need lean into bow for build to work but it's a next-level kit for Tonfa mains when all made up (and hearing your stats, it will fit you without performance penalty -- very nice). Will be a boss drop so pray for Kodama mats drop (Hunter blessing) going in to have Toyo forge it. If you are bow-shy, just build and clan for HP on bullseye or debuff/weakpoint-harvesting upon hit, something that pays dividends without gimping your go-to game. Lastly, keep an eye out for Flying Bolt cores now to start collecting in complement to which. Just some theorycrafting legwork.
You should only run setless, patchwork armour if early-game or before map 4 on DotSam, IMO. Spear, you'd mentioned, is baller but without advanced transitions in play like Flying Monkey, it's more or less just a rangy stick for scaredy cats. Kusa comes with a learning curve (easy to eat counter DMG in misstep) but was my main in the original, stubbornly so; has a many-faces moveset that juggles short and mid-long ranges -- think death by a thousand cuts and catch me if you can. I think Spear only looks good on Tonfa's arm on paper. In practice, Valiant Wanderer will take your DPS nuclear with A-scaling for Courage and I'd argue a focus on Nin should be your goal after that. For a weapon beyond bow and because VW will have a set req for Str, I'd run Odachi -- it's got poke and a sick skill-tree.
If you've a ways to go before you can farm for VW, I'd wholeheartedly run Hammers as secondary. With scaling in mind and because dudes often mix this up, don't ever swap Hammer for Axe; per your build, the synergy sits squarely with Hammers. Happy skull-crushing, samurai.