They never even hit their swords
ding ding ding! Thats one mistake self-proclaimed "expert katana" wielders today make. Katanas are not made to block, the sword is one giant razor. And if their is anything I know about, its razors. If a katana were to hit another katana which blocked the blow, both katanas would have damaged edges, edges that cannot be honed if the strike was a good one. Also a katana is extremely ineffective of cleaving. Thats right, no cleaving. Katanas are only effective when you hit the target, and pull the blade back down against it. Thats how they slice off limbs, thats how they do cool stuff.
Of course in RPs, we could get away with saying Ebony and Daedric katanas dont conform to these rules, since Ebony edges are reputed to cut through all, but the edge is still a razor and the sharper the razor, the easier it is to damage. Standard katanas, apply to realistic rules.
However I still feel Samurai were amazing warriors, but Knight vs Samurai is out of the question. Samurai's had many more open vital spots then a fully armored knight did, and the only way a samurai could win the fight with his katana is by finding an open spot (perhaps the arm pit) or penetrating the neck area of ringmail which would likely destroy the sword's edge, making the samurai even less effective against the enemy. Samurai could always whip out the jiu jitsu though, heavily armored knights on their back dont make for the best wrestlers.
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As for political roleplays and battle roleplays, Crazyjoker hit the nail dead on. Political roleplays have more administrative and governance features, while a battle roleplay will be the actual armies campaigning and clashing. You can always expect to see a crossbreed between the two, a lot more lenient in details and the 'nitty gritty' of things. For example, you can basically look at this guide and know what you'll expect to read in a battle rp. Weather, cold or heat, mud, terrain and everything comes into play.
PoliticalPolitical roleplays will have a lot of interaction with roleplayers (almost know armies fighting would be the hallmark of a true political rp) and the action comes in other forms. Expect to see romancing between figures, drunkeness, and many flawed characters. Racism, alcoholism, drug addiction, cowardice, and sixual deviancy are all commonplace in many political roleplays. It gives life to the characters and also the tools to which create weapons against your rivals. Finding out the queen of Camlorn is having an affair with the Prince and her son in-law gives you the chance to exploit that knowledge via spys, and blackmailing her. Now you just earned yourself a forced ally in Camlorn's court and her life along with the Prince's political career and respect are at your mercy. Marriage is commonplace as that is how many houses and cities were united in similar eras.
One thing to look out for, is doing nothing but writing letters to form alliances out of the blue. It takes alot more then letters, this should be a redflag of what your going to get in the roleplay, most likely it will be one of these....(look directly below)
Political WarSo the two vary greatly, but its never impossible to crossbreed them into their own roleplay. Political war roleplays usually have characters in administrative positions, throwing war around left and right, with less political motivations and actions then you'd see in a regular political roleplay. Although many roleplayers involved in these forget its a roleplay, and think it a RTS video game of just trying to be the guy in charge. Expect lots of betrayel.