I’ve given Earthrise Hoist the guns of Siege Prowl and Smokescreen. They are pegged into his arms in vehicle mode pointing forwards.
Since he didn't come with a weapon, I gave CW Brawl my spare T30 Blitzwing gun. I also used to give CW Bruticus Siege Megatron's sword-gun thing with the sword parts removed. It worked well as a big blaster for him, but I kinda like the sword better so I reverted it.
I use CW Sunstreaker's gun for him. I also shaved off the Heels on the hands so Battletrap in combined mode can hold guns.
RID2015 Sideswipe's sword works great with Siege Sideswipe and CW Prowl's Shotgun works with Siege Prowl Victoron's sword half works as a stand in Star saber for Optimus
Oh, that reminds me: I use Siege Soundwave's spare grey gun for Battletrap. Fits in perfectly with no modifications required.
I gave Pinpointer who came with Takara Legends Windblade to Siege Crosshairs, his original partner. Pretender Bumblebee's rifle to Titans Return Bumblebee. CW First Aid's axe to POTP Slash. Jazz' Pretender shell to his Actionmaster self. Same with Grimlock. The Actionmasters look much better compared to the Pretender inner robots. G1 Hun-gurrr's Sonic stun gun to POTP Hun-gurrr. G1 Quake's Targetmasters, Tip Top and Heater to TR Quake. They scale nicely with his Titanmaster Chasm in robot mode. Double Targetmaster Nebulans make good replacements for G1 Seeker null rays.
If you want your G2 Jetfire or Robot Masters R-Blade to have a G1 Jetfire style gun (Macross Valkyrie gun) then all you need is a Robotech Veritech Super Deformed Morpher released by Harmony Gold/Toonami in the early 2000's. The gun is the perfect size and the handle is a perfect fit for G2 Jetfire or R-Blade.
I just realised a larger bot can use POTP Bludgeon as a bludgeon, a shell of a good one! Apparently it's perfect for bashing skulls.The samurai that slams your eye! These puns write themselves. Here we have the aforementioned POTP Hun-gurrr weilding G1 Hun-gurrr's Sonic Stun gun. Robotmasters Wrecker Hook's morning star fits perfectly in Siege Megatron's hand. Watch this informative photo as Megatron uses the mace to stop Nemesis Pax from mugging him while also reminding him who Optimus Prime's true nemesis is. "Takes more than an edgy colour scheme and a bad attitude to do this job, young Pax!"