I found a script that deals damage in an area around you:
dragonslayer_trigger = (0, 0, 2, [
(key_clicked, key_j),
(neg|main_hero_fallen,0),
(get_player_agent_no, ":player_agent"),
(agent_get_wielded_item,":wielded_item",":player_agent",0),
(eq,":wielded_item","itm_dragonslayer"),
],
#(get_player_agent_no, ":player_agent"),
[#(agent_get_team,":player_team", ":player_agent"),
(get_player_agent_no, ":player_agent"),
(agent_get_position,pos1,":player_agent"),
(try_for_agents,":agent"),
(agent_is_alive,":agent"),
#(agent_is_human,":agent"),
(neq,":agent",":player_agent"),
(neg|agent_is_ally,":agent"),
(agent_get_position,pos2,":agent"),
(neg|position_is_behind_position,pos2,pos1),
(get_distance_between_positions,":dist",pos1,pos2),
(lt,":dist",300),
(particle_system_burst,"psys_game_blood",pos2,100),
#(particle_system_burst,"psys_boemfik",pos2,100),
(agent_play_sound,":agent","snd_man_die"),
(agent_play_sound,":agent","snd_metal_hit_high_armor_high_damage"),
(store_agent_hit_points, ":cur_hit_points",":agent",1),
(val_sub,":cur_hit_points",25),
(agent_set_hit_points,":agent",":cur_hit_points",1),
(agent_deliver_damage_to_agent,":player_agent",":agent"),
(agent_set_animation,":player_agent","anim_release_slashright_twohanded"),
(try_end),
])
Edit: if there was a way to mark all the enemies in the area(besides the one actually hit an maybe people with shields) and execute an attack on each of them it would be better
link to thread: http://forums.taleworlds.com/index.php/topic,62649.0/imode.html
not sure if works for mb warband or at all but I will test it right now(and knowing my luck I'll paste it into the wrong .py file and it won't even compile)