Although I guess it is sometimes not the highest priority, realistic walking in games ads to immersion, and like ambient noise is one of those things that you don't notice but makes you feel like you are really there. So I wanted to quickly suggest:

*Acceleration in walking/running - Add (or increase?) the acceleration time to get to full speed walk/run, to perhaps 0.5sec (?) for walk, 1.5 (?) for run.
*Step frequency linked with movement speed - Timing the walking animation so it corresponds precisely with character speed (ie. feet push backwards and ground moves at exact same speed), to prevent floating/moonwalking/iceskating feel to character movement. Easier said than done I realise, perhaps you are already planning this
*Subtle movement bob - I realise this is not doom but a slight superficial movement bob in first person mode would add to the feel I think.
*Slight delay to jump - 0.2sec (?) half crouch before jump. Running jump this would be slightly different I guess.
*Sprint feature - Run quicker for short period. Gives something to do on long foot journeys, adds pve/pvp quick escapes, potential for jumping crevasses etc.
*Footsteps audio - Quiet enough to not be distracting, again if possible timed with step frequency. Potentially, play a sound based on shoes, ground type, armour type (chain mail chink-chink).
*Jump/fall audio effect - In particular a good old crunch sound if you fall from a great height, or feet landing for lesser height.

I assume altering speed and jump size relative to agility trait is already planned?
 
Ok hope at least one of these ideas is useful! Thanks for making a fine game, looking forward to future developments!