How a player reacts and chooses for their character to act in a perceived situation is role playing.
Depending on the fun level or stimulation level of a game, this can include what is said or how a battle is fought.
However, application of any skill or knowledge follows the same concept for any resolution.
- Tactics and Strategy for fighting (both overall battle and the subtleties in one-on-one).
- Streetwise for survival, what to say, and who to say it to, where to find goods. Perhaps also how to fight and live.
- Diplomacy and Politics for social manipulation, subversion and intrigue (staying alive politically and socially, making allies or enemies - such as how we use our words in the forums).
I see a general discrepancy if characters must roll for a melee battle tactics and hand-to-hand tactics, but not for social interaction. This implies that no skill is required for social interaction, but skill is required for physical combat.
If this is an agreed state of play, that is fine. But there is still a discrepancy and it shows the focus of the game simulation is combat and melee tactics, and that social interaction is unimportant for "leveling" or taken for granted.
If character's social tactics do not require a skill roll for the purpose of role-playing a player's words, then surely for the sake of system equality it would mean that a player can also role-play their character's combat tactics even though the character would not have any command experience or battle wisdom. Depending on the tone of play, some games are run like this as well. It is just a matter of being conscious of the choice of play and the existence of the discrepancy of how resolution is treated between all skills (and the tone of the game).
Personally, I like to run games where characters have skills that equally indicate the scope and nature of what a character can do, and within this (and maybe a bit beyond, for fun) allow the player to choose, and sometimes roll as required.
The best sword fighter could be doomed if noone likes them.