H. P. Grice, "The multiplicity of being in Gricese"

Grice: "The verb 'to be' is actually composed of three different stems -- not only in Aristotle, but in Gricese."

CONIUGATVM	persona	s-stem (cognate with Roman "sit")	b-stem	w-stem (cognate with Roman, "ero")
MODVS INFINITVUM		the verb "sīn"	the verb "bion"	the verb "wesan"
MODVS INDICATIVM PRAESENS
	prima singularis: "ik" -- Oxonian "I"	"em" Oxonian, "am."	bium	wisu
	secunda singularis: "thū" -- Oxonian: "thou"	"art" Oxonian "art"	bis(t)	wisis
	tertia singularis: "hē" Oxonian, 'he'	"ist" (Cognate with Roman "est") Oxonian 'is'	*bid	wis(id)
	prima, secunda, tertia, pluralis	"sindun"	*biod	wesad
MODVS INDCATIVVM PRAETERITVM
	prima singularis			"was" Oxonian: "was."
	seconda singularis			""wāri" Oxonian "were"
	tertia singularis			"was" Oxonian "was"
	prima, secunda, tertia, pluralis			"wārun" Oxonian "were"
MODVS SVBIVCTIVVM PRAESENS
	prima, secunda, tertia, singularis	"sīe" (Lost in Oxonian after Occam)		"wese" (cognate with "was", and Roman, "erat")
	prima, secunda, tertia, pluralis	"sīen"		wesen
MODVS SVBIVNCTIVVM PRAETERITUM
	prima, secunda, tertia, singularis			wāri
	prima, secunda, tertia, pluralis			wārin
MODVS IMPERATIVUM
	singularis			"wis," "wes" (Cognate with "was" and Roman "erat")
	pluralis			wesad
MODVS PARTICIPIVM PRAESENT				wesandi (cognate with Cicero's "essens" and "essentia"
MODVS PARTICIPIVM PRAETERITVM				"giwesan"

The present-tense forms of 'be' with the w-stem, "wesan" are almost never used. 

Therefore, wesan is used as IMPERATIVE, in the past tense, and in the participium prasesens versions of 

"sīn" -- Grice: "I rue the day when the Bosworth and Toller left Austin!" -- "Now the OED, is not supposed to include Anglo-Saxon forms!") and does not have a separate meaning. 

The b-stem is only met in the present indicative of wesan, and only for the first and second persons in the singular.

So we see that if Roman had the 'est-sit" distinction, the Oxonians had "The 'ist'/"sīe"/"wese" tryad). 

Grice: "To simplify the Oxonian forms and make them correlative to Roman, I shall reduce the Oxonian triad,  'ist'/'sīe'/"wese" to the division actually cognate with Roman:  'ist'/'sīe." 

And so, I shall speak of  the 'ist'/'sīe" distinction, or the 'est-sit' distinction interchangeably."