There isn't much in the game for weapon or tactic loyalty. One who devotes themselves to one type of weapon or combat style should naturally be a little better than others right? My proposal would simply be a list at character creation. You can choose to pick nothing of course, and play the jack of all trades route. A little boring, but unarguably effective. This list would allow you to pick specialties that have built in bonuses and penalties, to help shape a character roleplay and personality wise. Some basic ones : Weapon Specializations - Can only pick one Melee Specialist - +40% melee damage, Cannot use guns, Can only use weakest bow Ranged Specialist - 1/2 Energy Cost for projectile weapons, -50% melee damage Demolitionist - Bombs and other explosives are added to your basic craft list and these items are easier to make and are more effective, -20% Melee Damage, +20% more energy used in ranged attacks Trap smith - All wiring and activation type things are added to your basic craft list and are easier to make, -20% Melee Damage, +20% more energy used in ranged attacks Second Weapon Specialization - Can only pick one Dual Wielder - +30% to weapon swing/fire speed when dual wielding, cannot use shields or two handed items (Other than the bow) Two Handed - +20% damage when using a two handed weapon, cannot use shields or dual wield Gun Nut - You deal 10% more damage with guns and they fire 10% faster, All other weapons deal 10% less damage and are 10% slower, Guns are cheaper at vendors Hunter - Bow attacks charge faster and you no longer slow down as you charge, You can't use guns Sword Specialist - You move 10% faster and swing 10% faster when wielding a sword, All other melee weapons suffer -20% damage Axe specialist - You deal 10% more damage and take 10% less damage when wielding an axe, All other melee weapons suffer -20% damage Spear Specialist - You jump 30% higher and gain slightly more reach when wielding a spear, All other melee weapons suffer -20% damage Playstyle Specialization - Can only pick one The Purist - Gain +20% movement speed and jumping height, Gain 20% more health, Cannot use tech The Tech Junkie - Techs take 40% less energy to use, 20% less overall health, Start with one piece of tech The Runner - +30% movement speed, Armor is 30% less effective The Tank - -20% movement speed,+15% more health, Armor is 30% more effective The Berserker - +20% movement speed and jumping height, Armor is 20% more effective, Gain passive health regeneration Only effective after striking an opponent in melee for a short burst, switching weapons disables the effect, You get hungry twice as fast all the time The Resource Gatherer - 20% faster mining/gather speed, No ill effects Just a basic idea I've been mulling around while trying to think of a way mechanically to both reward and enforce a character's playstyle. Sort of to help define the character in a way that sets him at least a little apart from others. It also gives a good excuse to actually have multiple characters. This list isn't comprehensive either, more could be added to it and of course it would need to be overall balanced with the game itself. My general numbers probably wouldn't work just at face value. They would need to be fairly impacting though, otherwise what would be the point? I also omitted flavor here, but I'm sure it would be pretty easy to write flavor in. Feel free to suggest notes to add to this idea and make it better. I'd love to actually have a character who is a little more than just a blank slate.
I know these are just examples, but I don't feel like restricting players from ever using certain items is a good idea. Even the most dedicated player will eventually get bored with using let's say just one handed items. Perhaps instead of (in terms of weapons anyway) putting a downside to everything, we should just give a bonus to something. Like, everyone does decently with akimbo and so do you, but you can take that specialist trait and get better at it. Maybe even make it possible to change later in the game via some high-level crafted virtual training pod. You get that, crawl inside and change your specializations (for a price). That is to prevent being stuck with something we don't fancy in late game. Different specializations could also be exclusive to certain races. Like for example Florans love stabbing things and can have either exclusive or just higher bonuses to spears, while they should be forbidden from specialising in flame weapons (like flamethrowers), since they're afraid of fire. A note about this training pod I mentioned. Aside from traits chosen with character creation, additional (let's go with Fallout-y terms) perks could be found in forms of blueprints (training programs) and used with your pod to train up to X perks that will add up to your traits. You could modify both of those as mentioned above. Perks would be separated from traits and give let's say more specialised bonuses (while traits would be more general), so those two don't do exactly the same, but can overlap (stack), thus giving better bonuses to one or more things.