Using grenades with a sword fighter is kinda strange. Grenades will alert lots of enemies out of line of sight. Sword fighting is, iirc, silent, while grenades create very loud sound, which makes enemies far out of line of sight to become alert and rush to join the fight. This is why i think that it would be much better to use Electrokinesis instead of grenades, as a sort of AoE ability, for a sword fighter: electrokinesis hits, while not completely silent, produce far less noise and will alert very nearby enemies only - most of the time, no extra enemies will be alerted at all.
In addition, 1st target of each electrokinesis hit gets stunned if it survives the hit; multiple Electrokinesis casts can be done per turn; 0 AP Eletrokinesis cast is possible with Premeditation feat; Electrokinesis never misses (while grenades sometimes miss even with high Throwing skill). In terms of skill points investment, maxing out Psychokinesis is comparable skill point investment to developing somewhat high Throwing for grenade accuracy and somewhat high Chemistry for crafting top tier grenades. And while having low Willpower lowers damage of Electrokinesis, it'd still be useful as both damage dealing and crowd control (via stun) even at 3 Willpower. I've played Willpower 3 Psychokinesis characters, having it as a support skill, in Domination difficulty, and for me it worked very well.
P.S. I can't offer any advice on sword fighting itself, as i never did any so far - sorry.
